INVESTIGATORS believe the mastermind of the synchronised bombings in London fled the country long before the attack. He would have travelled on the Underground network, studied timetables and known his way around major stations such as King’s Cross. Security chiefs say he would have organised his own escape with the same precision.

The hunt for the organiser of the London cell has spread worldwide with police studying suspects from Scandinavia to the borders of Pakistan and Afghanistan. Some of the names being circulated are linked to al-Qaeda’s high command, while others are said to be veterans of terror training camps who have been careful to steer clear of radical groups they knew would be kept under surveillance.

The police list also includes a number of British-based radicals of mainly North African origin. A major problem for Scotland Yard is that a number of these men are on the run in countries such as Iraq where they remain beyond the reach of any authority.

One senior police source said “The pattern of these attacks is that the masterminds make sure they are well clear before the bombs explode.”

The meticulous timing of the Tube bombings also leads investigators to think that the architect is likely to have been involved in planning other terror operations. In Spain, police say the radical leader who planned the bombing of four Madrid commuter trains in March 2004 has never been found.

Experts from a dozen countries are already assisting the Yard, including a team from Spain who have handed over files on some of the alleged architects of the Madrid bombings who are still on the run

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Their main focus is on Mustafa Setmariam Nasar, 46, a Syrian with joint Spanish nationality who lived in North London in the mid-1990s. As The Times revealed last week, he left Britain to start up a terror training camp in Afghanistan before the September 11 attacks where he groomed scores of young British recruits.

Nasar, who has a $5 million (£2.9 million) bounty on his head and who lived in Neasden with his wife and child, has a record of setting up “sleeper cells” wherever he has been.

Two of his lieutenants in the Madrid operation were North Africans who carried British passports in the names of Burgess and Frost. They too have disappeared. There have been various sightings of Nasar, with the latest intelligence reports suggesting he is now in Iraq.

Reports from Denmark yesterday said that police have been asked to track down Abu Rashid, a fellow Syrian, who was Nasar’s deputy at one of his training camps in the mountains straddling the Afghanistan-Pakistan border.

Rashid is said to have disappeared from his home in Braband, near Aarhus, but police say that he was kept under only loose surveillance by the Danish authorities.

Major Soeren Bach of the Danish Military Academy has described his country as a safe haven for Islamic radicals, saying: “We have decided to leave these people in peace because it is easier to do this rather than get into a legal battle with them.”

The attacks in London triggered a massive security operation in Italy, where police arrested 142 people over the weekend and issued deportation notices for 52 illegal immigrants.

As some of the suspects on Britain’s list are already in custody abroad, British police will ask permission to interview them in prison.

One figure was named as Zeeshan Hyder Siddiqui, 25, a British national who is in prison in Pakistan and is alleged to be among those schooled in bomb-making at one of Nasar’s camps. Siddiqui is from West London and studied physics at a university in the capital.

The Moroccan authorities are still hunting for two clerics said to have helped to plan a string of bomb attacks in Casablanca in May 2003. The two, who cannot be named for legal reasons, are understood to have visited Britain a number of times.

Lord Stevens of Kirkwhelpington, who retired as Metropolitan Police Commissioner in January, argued that everyone involved in this atrocity would be found closer to home. He wrote in his News of the World column “any hope the attackers came from abroad was dangerous wishful thinking. The bombers will be apparently ordinary British citizens, young men conservatively and cleanly dressed and probably with some higher education.

“Highly computer literate, they will have used the internet to research explosives, chemicals and electronics. They are also willing to kill without mercy — and to take a long time in their planning.”

His remarks angered race relations groups. Massoud Shadjareh, chairman of the Islamic Human Rights Commission in London, said the claims were unfounded and threw suspicion on all Muslims in Britain.

He said: “He has, without doubt stirred up racial tensions at a time when we need unity.” Lord Stevens is confident the public outrage will “unleash a tidal wave” of information from the Muslim community.

He estimates that up to 3,000 British-based militants passed through training camps over the past decade. Details are scant of what became of these recruits. Some are known to have fought in Kashmir, Chechnya and Iraq, but the majority slipped back to Britain.