The discovery of Osama bin Laden's hideaway in a city at the heart of Pakistan's military establishment today revived questions about alleged links between al-Qa’ida and elements in the country's security forces.
The Pakistani authorities were quick to insist that they had no prior knowledge that the world's most wanted man was living in the garrison town of Abbottabad, only a few hundred yards from the military academy known as Pakistan's Sandhurst.
But an MP with strong links to Pakistan said he was "flabbergasted and shocked" that the al-Qa’ida leader could have found a safe haven in a town where thousands of troops are based.
Khalid Mahmood, chair of the parliamentary all-party group on tackling terrorism, said: "I am absolutely flabbergasted that the authorities either allowed that to continue or weren't aware of it.
"If they weren't aware, it was huge incompetence. There are certainly huge issues to be considered."
Abbottabad could be compared with a British town such as Aldershot for its dominance by the armed forces, said Mr Mahmood.
"If he had been in the mountains of Peshawar, that might have been acceptable, but in a key town in Pakistan, I am amazed that that has been allowed to happen. How is it that they have never found him there?"
Elements within Pakistan's ISI intelligence agency have long been accused of sympathy for militant Islamism and of aiding the Taliban in Afghanistan and insurgents in Kashmir as part of their regional rivalry with India.
Even after former president Pervez Musharraf signed up to the US-led war on terror in 2001 - taking billions in American military aid in return - suspicions persisted that no real effort was being made to root out extremism in Pakistan.
A report by the House of Commons Foreign Affairs Committee in March stated: "Prior to 2001, overt Pakistani support in the form of diplomatic recognition to the former Taliban government was combined with more clandestine backing for proxy terrorist groups in Afghanistan, in many instances created and shored up by the ISI... which continues to drive foreign policy, in spite of the existence of a civilian government.
"Today, Pakistan's border areas with Afghanistan provide ungoverned space from which al-Qa’ida and other militant and organised crime groups operate."
The committee warned last year of "a lack of uniform and widespread support within the military and ISI for the need to tackle the Afghan insurgency from within Pakistan".
And Prime Minister David Cameron made clear last year that there were continuing suspicions about Pakistan's activities by saying that the UK would not "tolerate in any sense the idea that this country is allowed to look both ways and is able in any way to promote the export of terror".
MI5 chief Jonathan Evans warned last September that around half of all "priority plots and leads" related to terrorism in the UK were linked to Pakistan - though this was down from 75%, thanks to pressure being put on al-Qa’ida in the country.
British confidence in Pakistan's commitment to tackling terrorism has been bolstered by President Asif Ali Zardari's military operations to establish control over tribal areas such as the Swat Valley and South Waziristan, which had been used as a base for attacks both in Afghanistan and Pakistan.
A new National Security Dialogue saw Mr Cameron and the UK's military and intelligence chiefs visit Islamabad last month to talk with their Pakistani counterparts and offer counter-terrorism assistance.
Pakistan's High Commissioner in London Wajid Shamsul Hasan insisted today that Islamabad had no idea of bin Laden's whereabouts until the US operation which killed him.
"Nobody knew that Osama bin Laden was there - no security agency, no Pakistani authorities knew about it," Mr Hasan told BBC Radio 5 Live.
"The fact is that the Americans knew it and they carried out the operation themselves and they killed Osama bin Laden and then later our president of Pakistan was informed that the operation was successful, and that's it."
But Foreign Affairs Committee (FAC) chairman Richard Ottaway said: "Unfortunately, I am not sure that the government of Pakistan speaks for the whole of Pakistan. It is a divided country with lots of tribal loyalties, and there are clearly internal divisions within Pakistan's security services.
"President Zardari met the committee when we went there last October and we were impressed by him and his willingness to try to work towards a stable world, but there are elements inside the Pakistani administration who do not share his position."
And Labour MP Mike Gapes, a serving member and former chairman of the FAC, said there were "a lot of questions" for Pakistan to answer.
"We have known for a long time that al-Qa’ida and Afghan Taliban elements were based in Pakistan and they still are, but the fact that bin Laden has been found in a huge complex in the middle of a military garrison town - rather than in some remote rural area - leads you to wonder how on Earth he has been able to live in this place," said Mr Gapes.
Foreign Secretary William Hague acknowledged that there had been a "general assumption" that bin Laden was hiding in the mountainous tribal regions of Pakistan rather than the area around the capital, Islamabad.
But he added: "I don't think we're surprised by anything any more."
Mr Mahmood said the decision to bury bin Laden at sea was likely to inflame passions among sympathisers, though it was in line with Muslim practice of laying people to rest within 24 hours of their death.
"Burying him at sea will, I think, cause some anger amongst his supporters, but it is a no-win situation, because had they buried him somewhere, that would have become a shrine for his followers," he said.
"We have now got to be very vigilant about possible reprisals from offshoots of al-Qa’ida.
"I think it is time also for the Muslim countries to deal with this issue of extremism through their own resistance to the preaching of people like bin Laden. They have to stand up and denounce what he stood for and what he was."
Professor Anthony Glees, director of the Centre for Security and Intelligence Studies at the University of Buckingham, said the US government would now face questions over why it took seven years to capture bin Laden and how he came to be hiding so close to the Pakistani capital.
"It is very important for the prestige of the US that they have finally got him (bin Laden) but questions will be asked, such as, how on Earth they didn't manage to get him before?
"There will also be questions for the Pakistani intelligence agency. He was hiding about 52 miles from the capital of Pakistan.
"To have hidden there, to have evaded the Americans for we don't know how long, and then to have been found down the road from Pakistan's capital Islamabad will be seen as embarrassing and it will be politically difficult."
And he said the nature of the killing - its timing and location - laid bare the "difficult" relationship between Pakistan and the US.
"We will have to watch very closely to see what the impact on Pakistan is going to be," he added.
"It could be that the US will be seen as interventionist and all the work that President Obama has been trying to do, distancing himself from the actions and interventions of his predecessor, have now evaporated."
Pakistan's High Commissioner in London defended the Pakistani security services and insisted they were trusted, despite the fact they were not informed in advance of the US operation to kill Osama bin Laden.
Mr Hasan suggested bin Laden might have chosen Abbottabad to reside as a "safe haven" but said criticism of Pakistan was unjustified.
He told Sky News: "This operation was conducted by the US forces in accordance with the policy of hunting down Osama wherever he was supposed to be. They successfully eliminated him and subsequently they informed the president of Pakistan this morning of the event.
"There has been some criticism in the media today about having Osama in our midst in Abbottabad. The fact is, Osama has been a nomad, a gypsy, who has been travelling from one place to another. He has been moving from one place to another every night, every day, every now and then.
"Abbottabad, probably he has chosen as a sort of safe haven, in the sense that it was out of the main focus of terrorist activities and it was a peaceful place and he thought that he would mix up with the local people and find refuge there.
"He did succeed at that but then he left some footprints which were tracked down and he was eliminated by the American forces and the government of Pakistan's cooperation."
He suggested that the Pakistani security forces had not been informed in advance because "probably the Americans came to know of it and there was no time to get others involved in it and they carried on on their own".
President Obama said earlier that he was first briefed on possible leads to bin Laden last August.
Mr Hasan dismissed the suggestion that there was a lack of trust between US and Pakistani security agencies as "rather humorous".
He said: "There is no lack of trust. The Americans have been very clear and categorical that they trust us.
"The government of Pakistan has been a very active partner with the American intelligence agencies and they have been cooperating with each other at each and every step. They have successfully helped the Americans in carrying out the operation."
Mr Hasan said the killing of bin Laden was a "major setback" to al-Qa’ida and other extremists. He said Pakistan had been "the worst victim" of terrorism.
He said: "Pakistan has played a very significant role in this war against terrorism and we are proud of it.
"It is Pakistan's stated policy not to allow its territory to be used for any terrorists, and we will continue to do that."
Nigel Inkster, a former assistant chief of MI6, said the discovery that bin Laden was hiding in Abbottabad suggested he may have been receiving protection from elements of the Pakistani intelligence services.
"There are questions, obviously, that arise out of this as to whether elements in the Pakistani intelligence community probably judged that it might be better to keep Osama bin Laden safe rather than risk the opprobrium that might attach to being in some way responsible for his death or capture," he told BBC Radio 4's The World At One.