Up to 10 terrorists from north Africa and Saudi Arabia have mounted surveillance operations on vulnerable commercial targets such as big banks and shopping centres, according to security sources.

They have also received intelligence that some of the suspects have already made “dummy runs” in preparation for possible suicide car bombings.

Warnings of a prospective attack by Al-Qaeda have been given to ministers by Eliza Manningham-Buller, MI5’s director-general. She has also told MPs and peers on the parliamentary intelligence and security committee of the Al-Qaeda “sleepers” conducting surveillance.

Many are integrated so deeply into the Muslim community that they are proving almost impossible to detect. Some are believed to be British citizens.

The disclosure came as David Blunkett, the home secretary, yesterday admitted for the first time that attempts to carry out violent attacks against Britain had been foiled. “These are the kind of things that counter-terrorist (operations) are designed to foil and (the security services) are doing this all the time,” he said.

The Al-Qaeda units, thought to be based in the Midlands and the north of England, have investigated the scale of security at synagogues and Jewish schools and community centres. However, intelligence on their plans is sketchy because MI5 has so far failed to penetrate the units.

Last week Sir John Stevens, the Metropolitan police commissioner, confirmed that Britain was on its highest state of alert since the September 11 attacks in 2001. Security was heightened after MI5 received warnings of an imminent terrorist attack 10 days ago.

At least 18 more people died in attacks on two Iraqi police stations yesterday. Amid the surge of deadly bombings in Iraq and Turkey, the US government issued a fresh warning on Friday about possible terrorist violence to mark the end of the Muslim holy month of Ramadan this week.

At the same time detectives from Scotland Yard’s anti- terrorist branch have started to sift through the wreckage of the British consulate and the HSBC bank in Istanbul for clues to the bombers behind last Thursday’s synchronised suicide attacks.

The death toll rose to 30 yesterday. It includes 10 consulate staff, of which three were British. This brings to more than 50 the number who have died in Istanbul following last weekend’s two synagogue blasts in the city.

Among the three Britons were Roger Short, the 58- year-old consul-general and a father of three, and his personal assistant Lisa Hallworth, 38. Hallworth’s mother Sylvia said she had been advised it was not safe to travel to Turkey where she wants to recover Lisa’s body.

The 27-year-old fiancée of Graeme Carter, a British tourist, is brain dead and will not recover, doctors at Istanbul’s Taksim hospital said last night. The couple were both pulled alive from the consulate ruins.

At first Carter thought Hulya Donmez had been blown to pieces. Then he was told she had survived. Yesterday doctors said she was still on a life-support machine but they had no hope of her surviving.

Security officials now believe the attack was carried out by local Islamists under the control of Al-Qaeda trainers. Turkish police were yesterday interviewing several people about their links to the suicide bombers.

The Turkish prime minister Tayyip Erdogan said the four bombers who carried out last week’s attacks were all Turkish citizens. He said it was a matter of “shame” for Turkey that its own citizens had murdered so many.

As security was tightened at British embassies across the world, a senior committee of MPs and peers was preparing to attack the government’s plans to protect Britain from terrorist attack. In a report to be published on Friday, the committee will say that the proposed Civil Contingencies Bill has “potentially dangerous flaws”. MPs on the committee say the bill is “too little, too late”.

The committee’s chairman, the former Labour defence minister Dr Lewis Moonie, will criticise the bill for failing to provide any new money to pay for counter-terrorist and emergency planning. Also, the committee believes that absence of information about the new emergency powers ministers will get after a terrorist attack makes it “impossible for local authorities and other bodies to estimate the cost of the responsibilities they would expect to undertake”.

One of the most serious flaws, it says, is the absence of any new funds to help local authorities prepare to cope with an attack in which hundreds or even thousands of people could be killed.

It says the Cabinet Office is providing just £19m for emergency planning which, from next year, can be plundered by councils to pay for other services. The committee believes this money should be at least doubled and that it should continue to be “ring-fenced” so that councils cannot raid it.

Under the plans, ministers will have powers to cordon off and forcibly evacuate large areas. They will also be able to close down the internet and telephone systems.

Explore UK News

• Crime News

• Education News

• Health News

• Science News

• Scotland News

Times Recommends

• Anne Darwin's performance of a lifetime
• Renaissance for canals as new boaters come aboard
• Case study: forced to marry a cousin at 17