Mystery surrounds convenient arrest of the al-Qa'ida mastermind 'behind 11 September'

The United States badly needed a big victory in its war on al-Qa'ida to counter those critics who said that the violent and fanatically anti-Western network represents a far greater and more immediate threat to Americans than Iraq.

And now, just as its generals and Pentagon strategists apply the finishing touches to their plans to invade Baghdad and topple Saddam Hussein, America says this is precisely what it has secured.

Pakistani agents, who have been working with the CIA and FBI, have, with immaculate timing, captured a man who is, by their account, almost as important as Osama bin Laden himself, an alleged mastermind of the 11 September atrocities that set off the current global crisis, a man of such criminal genius that – according to The Washington Post – he is known within the counter-intelligence world merely as "The Brain". Almost every big attack against the Americans and their allies by Islamist extremists over the past decade has been linked with Khalid Sheikh Mohammed, who was arrested in Pakistan at the weekend and – amid some confusion last night over whether he was in US or Pakistani custody – spirited off to a secret location.

He has been described by the White House as the central planner of the 11 September attacks on New York and Washington and a "key al-Qa'ida planner". He has been referred to by others as al-Qa'ida's chief military operations officer, a conduit for money, people and plans throughout the Middle East, south Asia and Europe.

There have been suggestions that he was involved in the bombing of US embassies in Kenya and Tanzania in 1998, in which 224 people were killed.

Intelligence agents in the Philippines believe he was part of a cell that plotted to kill the Pope in 1995. His name has been linked with the attack on the US warship the USS Cole, in Yemen, in which 17 American sailors were killed in 2000.

His was the hand that allegedly drew the knife across the throat of a terrified Daniel Pearl, the Wall Street Journal reporter kidnapped and killed in Karachi as he was investigating Islamist extremist groups. He has, it is said, 27 aliases, speaks five languages, and is – say the Americans – as smooth and unruffled in a sleazy nightclub or in a restaurant in North Carolina, where he studied engineering in Chowan College, as he is in a staunchly conservative Islamic home in Pakistan.

If all these allegations are true – and it remains a significant "if" – he is about as breathtakingly ruthless and sinister as they come, a man with the blood of thousands of people on his hands and a $25m American reward on his head.

His "career" makes intriguing reading, although it is important to note that much of the details have been made public by the tireless but unnamed "US sources" who have an interest in presenting their opponent – and now captive – as a very big fish indeed. He was born in Kuwait some 37 years ago, fourth son of Sheikh Mohammed Ali, a prominent preacher at the al-Ahmadi mosque. But the family comes from the Pakistani province of Baluchistan, the wild lands bordering Afghanistan which are a hotbed of hardline Islamist anti-Westernism.

While still in his teens in Kuwait, he is said to have joined the Muslim Brotherhood, founded in Egypt in 1928 and the largest international Islamist organisation.

In 1983, he went to Chowan to study, where he is remembered for being highly intelligent and rigidly conservative, and for keeping his distance from non-Muslims and non-Arabs. Before long he was raising money for the CIA-funded Afghan "jihad" against the occupying Soviets by selling second-hand clothes.

Six months after graduating in mechanical engineering, he is believed to have moved to Peshawar in north-western Pakistan, where he later linked up with Bin Laden.According to the Financial Times, which has investigated his career in detail, he devoted himself to the cause of the Afghan mujahedin for some five years.

He is related to Ramzi Ahmed Yousef, who is serving life in the world's most secure jail, the "supermax " in Florida, for the 1993 bombing of the World Trade Centre – another attack that some have chalked up to Khalid Sheikh Mohammed. So, too, has a lorry bomb in April last year that detonated outside a Tunisian synagogue, killing 21 people, many of them Germans.

According to The New York Times, his importance within al-Qa'ida did not become clear to American investigators for some months after 11 September, when his name began to emerge during interrogations with al-Qa'ida operatives as a crucial player, and possibly the link between the 19 hijackers and the network's leadership. American officials say it is possible he visited the hijackers in Hamburg, Germany. Last year, the joint congressional inquiry into the terror attacks was critical of the CIA for not recognising his importance within al-Qa'ida before the attacks.

He had first come to the attention of the CIA and FBI six years earlier, as a member of a small group of militants, including Ramzi Yousef, in the Philippines. They were behind a plan simultaneously to bomb 11 US airliners – a scheme in which their operatives would buy tickets for up to a dozen American commercial flights to destinations around the Pacific, plant bombs on board and then get off at intermediate stops before the explosions.

This was thwarted by a fire in the apartment in Manila where they drew up the plan, after which Filipino authorities discovered a computer containing details of the proposed attacks. His role was enough to secure an indictment by a grand jury in the United States.

He has, it appears, come close to arrest on several occasions. In 1996, US intelligence received a tip-off that he was living in Qatar, but when an FBI team arrived in Doha to arrest him, he had disappeared. He is also thought to have spent time in South America, Germany, and Afghanistan. He was to execute another apparently close escape in Karachi last year.

By the late 1990s he was in Afghanistan and, it appears, planning the biggest atrocity of them all. In May 2002 he told the Arab satellite television channel al-Jazeera: "About two and a half years prior to the holy raids on Washington and New York, the military committee held a meeting during which we decided to start planning for a martyrdom operation inside America." It was a complex operation. According to the FT's investigation, he played a part in the intricate financial arrangements for the 19 hijackers, allowing them to pay their way while in the US. A central figure in that planning was Mustafa Ahmed Aden al-Hawsawi – the man to whom three of the hijackers wired a total of $25,000 of unneeded funds just before they went to their deaths.

Bank records showed that Hawsawi had an extra Visa cash card, in another name. When investigators saw the photo ID taken for the application form for the card the face was Khalid Sheikh Mohammed.

The reliability of such reports cannot be established until he is brought to trial. But if even half the claims the authorities are making for this arrest are true, it is good news for the war against terror.

The Hunt for Al-Qa'ida continues

By James Palmer

The arrest of Khalid Sheikh Mohammed is a major coup for the US, which has been under fire for seeking war with Iraq and letting the hunt for al-Qa'ida operatives take a back seat. The failure to capture Osama bin Laden has embarrassed the US. It is not known whether he is alive or dead, but recent reports indicate he may be hiding on the border of Afghanistan and Pakistan.

Mullah Mohammed Omar, the Taliban leader and Bin Laden's former protector in Afghanistan, has proved equally elusive, along with Ayman al-Zawahri, al-Qa'ida's second-in-command and believed to be Bin Laden's doctor and religious mentor. A third key figure, Mohammed Atef, the military leader of al-Qa'ida, is believed to have been killed by US raids in Afghanistan. Atef was accused of encouraging the attacks on US forces in Somalia in 1993 in which 18 died, and of directing the US embassy bombings in Kenya and Tanzania in 1998. Last month, Mounir al-Motassadeq became the first man convicted over the 11 September attacks. He was accused of financing the hijackers and was found guilty of being an accessory to mass murder. He was jailed for 15 years. The first person indicted for 11 September was Zacarias Moussaoui, a French Moroccan detained on immigration charges in August 2001. He is awaiting trial in the US. Western intelligence officials believe the missing link in the conspiracy is Ramzi Binalshibh, a Yemeni national. He is also accused of involvement in the bombing of the USS Cole in Yemen in 2000, in which 17 sailors died. He was arrested in Pakistan last September. But the most senior member of al-Qa'ida to be captured up to now was Abu Zubaydah, a "member of Osama bin Laden's inner circle".

Mohammed Haydar Zammar is being held in Syria and is believed to have been a recruiter of the hijackers. In Britain, Abu Qatada, a Muslim cleric, is being held on suspicion of being an al-Qa'ida fixer.