Armoured vehicles and hundreds of troops were drafted in to protect Heathrow airport yesterday after security services received intelligence of a terrorist threat.
An additional 1,000 police officers, many of them armed, were deployed from 6am along with 450 troops who patrolled the perimeter of the airport in west London and its four terminals in Land Rovers and reconnaissance vehicles armed with 30mm cannon and machine guns.
Scotland Yard said the move was a "precautionary measure" linked to concerns that al-Qa'ida or associated groups might use the end of the Muslim festival of Eid as an excuse to attack. The festival runs from today until Saturday.
Scotland Yard refused to reveal the substance of the threat but terror experts said it pointed to a possible missile attack on a plane similar to the one carried out by al-Qa'ida terrorists in Kenya last year. Chris Yates, an expert with the specialist journal Jane's Airport Review, said: "The key here is perimeter security. We can put all sorts of technology and security in airports but it doesn't take an Einstein to work out that you can park around the perimeter and launch something like a missile."
Hours after the soldiers arrived, police began stopping vehicles under the flightpath near the village of Wraysbury in Berkshire. In Windsor, which is also under the main Heathrow flightpath, soldiers patrolled the town and troops manned entrances to Windsor Great Park and searched wooded areas. Security was also bolstered at unspecified sites linked to London's economic and transport system.
At Heathrow, troops from the 1st Battalion the Grenadier Guards and the Household Cavalry Regiment patrolled the airport complex. The convoys of army vehicles and police cars included several Scimitar armoured reconnaissance vehicles which spent short periods at the terminals and other sites. Soldiers, dressed in combat fatigues and carrying rifles, patrolled on foot in teams of two or three around the terminal buildings. Scimitars, which resemble small tanks, can travel at up to 50mph and were last deployed at Heathrow in 1994 after a failed IRA mortar attack from outside the perimeter fencing. The shells failed to explode and no one was injured.
In a statement Scotland Yard said: "From time to time it is necessary to raise levels of security activity. We think it is prudent to do so now. The current strengthening of security is precautionary and is related to action being taken in other countries and the possibility that the end of the religious festival of Eid may erroneously be used by al-Qa'ida and associated networks to mount attacks."
Massoud Shadjareh, chairman of the Islamic Human Rights Commission, based in London, said it was "extremely provocative" to link a possible attack with Eid. "It is like suggesting that Christians would use Christmas to bomb Jewish, Muslim or Buddhist communities, he said. "It is unbelievable rubbish."
Sheikh Omar Bakri Mohammed, leader of the Islamic group al-Muhajiroun, claimed yesterday that radical Muslims were prepared to act as suicide bombers. He said people should stay away from locations such as financial institutions and government buildings. "I would be careful, there are people who are in the UK, these are people who are supporters of al-Qa'ida and these people are Islamically speaking, they are people who feel they have a right to retaliate back," he told the BBC.
Downing Street said the Heathrow deployment was "an ongoing operation in relation to a specific threat" personally authorised by the Prime Minister. Tony Blair's spokesman said: "The Government and the security authorities are taking whatever action they believe necessary to protect the public."
Last week the US national terror alert was raised from yellow to orange, the second highest category, after a "high-risk" intelligence warning of a terrorist attack.
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