Official “stop and search” guidance just issued to thousands of Metropolitan police officers indicates that police fear the bombers may be planning to change their tactics.

“Terrorists will try to use our actions against us and will adapt their methods (use women or even children),” the document states.

The paper contains advice to officers exercising their powers under section 44 of the Terrorism Act 2000. The rules govern the conduct of the 6,000 officers who have been deployed across the capital to stop a possible third terror cell following on from the July 7 atrocities and the failed July 21 attacks.

The paper was released this weekend on the order of Sir Ian Blair, the Metropolitan police commissioner, in an effort to defuse the row over claims that police are singling out Asian and black men during street searches.

Under the rules, Met officers have been told to avoid “racial profiling” and “not to focus on specific groups”. The advice adds: “Be aware that there is no specific racial, ethnic, sexual or religious profile for terrorists.”

Blair insisted the new advice was not dictated by political correctness. “Everything’s got to be intelligence-based,” he said.

“If we said the only people to be searched are young males who are of Caribbean or Asian or north African appearance it would be handing the objectives to the terrorists and they would immediately change their tactics.”

He was talking after Ian Johnston, chief constable of the British Transport police, which guards the Tube and train network, suggested his officers had been told to single out Muslim and African men as the most likely terrorist suspects. “We should not waste time searching old white ladies,” he said.

The disclosure of the Yard’s guidance comes as transport police draw up plans for elite “sniper squads” to combat the threat of suicide bombers. Between 150 and 200 firearms specialists are to be recruited as part of a nationwide drive to stop further attacks on the transport system.

The unit will be modelled on Scotland Yard’s SO19 firearms unit, whose officers shot dead Jean Charles de Menezes, an innocent Brazilian, after mistaking him for a suicide bomber 16 days ago.

The move will see armed officers regularly patrolling the Underground and the rail network for the first time. Crack sniper squads and close-quarter “hit teams” such as the one that killed Menezes will be on permanent stand-by to deal with suspected suicide bombers.

Blair said he planned to recruit several hundred more armed officers to bolster the number already licensed to carry guns. He is also in talks with the Home Office for an extra 500 or 600 officers to boost the Met’s counter-terrorist capability. The move would effectively double the size of the anti-terrorist branch.

Blair also repeated his call for a national border control agency to make it more difficult for terrorists to enter and leave the country. The Sunday Times revealed last week that Hussain Osman — also known as Hamdi Isaac — one of the men arrested over the failed July 21 attacks, had managed to leave Britain on the Eurostar train.

MAN ON TUBE CHARGES

Yassin Omar, 24, has been charged over one of the failed attempts to bomb three London Tube trains and a bus on July 21. He faces charges of conspiracy to murder and possession of an explosive substance in connection with the bombing attempt at Warren Street station. Omar, from New Southgate, London, will appear before Bow Street magistrates tomorrow.

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