UK rail travellers warned

The discovery of a videotape claiming Osama bin Laden’s terror group carried out the Madrid bombings and warning that more "blood will flow", turned the spotlight once again on the threat posed by the extremists.

Britain’s security services are still believed to be on their second highest level of alert - "severe general", which was raised from "substantial" last year following intelligence about plans by al-Qaeda supporters from North Africa.

The alerts are for the security services only, including the police, the army, MI6 and MI5, and are not usually made public. They were introduced after the Bali bombings to help those involved in the fight against terrorism respond to changing circumstances.

A spokesman for the Home Office said yesterday: "Since 11September there has been a heightened sense of threat.

"At present there is no specific threat, but if there is we will make that known where that would help people to avoid a particular attack."

Meanwhile, Defence Secretary Geoff Hoon said the Madrid rail bombings underlined the need for rail passengers to be alert and to report anything suspicious to the authorities.

"If there are any packages, any briefcases and suitcases that don’t appear to belong to any particular individual they should ask each other," he told BBC1’s The Politics Show.

"They should ask fellow passengers, they should bring it to the attention of guards and those in authority. It is that kind of action that can make an enormous difference if the public do co-operate, as I am sure they will."

Mr Hoon’s comments followed those of the country’s biggest rail workers’ union, the Rail Maritime and Transport Union, which called for increased security on the UK’s rail network in the wake of the bombings.

Senior Scotland Yard officers were reported to be reviewing security measures already in place in London.

British Transport Police have confirmed that plain-clothes counter-terrorism officers will conduct patrols on the London Underground system, and uniformed officers are to begin stop and search checks at Tube stations as vigilance is stepped up.

Underground passengers have been warned to make their own checks for unattended baggage, British Transport Police said, and a new poster campaign will be launched this week.

Deputy Assistant Commissioner Peter Clarke, head of the Metropolitan Police Anti-Terrorist Branch, said: "The despicable attacks in Madrid show only to closely that the threat of terrorism remains very real.

"London continues to be on a high level of alert and security across the capital remains under constant review."

Paul Rogers, from the Department of Peace Studies, at the University of Bradford, said that in addition to trying to prevent a terrorist attack by tightening security, greater efforts had to made to cut off support for the terrorist organisations.

"There has to be a further improvement in security and intelligence services, but beyond that, what I think we have not yet done is really get to grips with why these groups have a lot of background, basic support," he said.

"It is very difficult to deal with the leaderships of extremely radical groups bent on this kind of action, in fact it is probably impossible at present.

"But these groups depend on a much wider range of people, and I think we have got to put more effort in the longer term to undercutting that very support, otherwise any talk of winning a war on terror is very short sighted."

He continued: "Because of the destruction of the Taliban regime in Afghanistan, al-Qaeda and its affiliates have become much more disperse, they are not centred on any one country."