Fears of a terrorist attack on France have intensified following threats to Prime Minister Jean-Pierre Raffarin from a radical Islamic group.

In a letter addressed to Raffarin and copied to leading French newspapers the group, calling itself 'Servants of Allah the Powerful and Wise', has attacked the French government's plans to ban Islamic headscarves in schools.

It said the decision was "an unjust aggression", adding that France had put itself on the list of Islam's worst enemies.

In recent weeks the French authorities have also received threats from another little known group -- AZF -- which claims to have planted several bombs along the country's rail network and threatened to explode them unless it was paid millions of pounds.

Earlier warnings from AZF led to the discovery of an explosive device underneath a railway line in central France last month.

The warnings come as European security chiefs prepare to meet in Brussels to discuss ways of meeting the threat from Osama bin Laden's Al Qaeda sympathisers who are believed to be responsible for last Thursday's Madrid bomb attacks.

In London Metropolitan Police Commissioner Sir John Stevens and Mayor Ken Livingstone have jointly warned that the UK is now an inevitable target for international terrorists.

Sir John told a press conference in London that a team of senior police officers were in Madrid to see what lessons could be learned from the Madrid bombings to improve UK security.

He told a news conference, "Since September 11, there have been 520 arrests, half have been charged with an offence and there are 90 about to go through to court. We do know that we have actually stopped terrorist attacks happening in London but, as the prime minister and home secretary have said, there is an inevitability that some sort of attack will get through but my job is to make sure that does not happen.

"We are not just talking about the Tube and the rail system. We are talking about buses, nightclubs, pubs and roads. We know from experience in Bali that Al Qaeda attacks clubs. There is a need for everyone to be alert.

"We are looking to see if there are specific things we can learn from Madrid in terms of who was involved and whether we should change our tactics. The things we have leant, we will put into force."