One of the ringleaders had lived in Hamburg

And others suspected of planning future attacks in Europe have been arrested in recent days in Italy, Germany, France and Britain.

Both US President George W Bush and Britain's Prime Minister Tony Blair have repeated that the "war on terrorism" is not directed at Islam or at Muslims.

Mr Blair even went on an Arabic TV station to deliver the message in person.

He and Romano Prodi, the President of the European Commission, have both publicly met Muslim leaders to stress their trust in the peaceful nature of the Islamic faith, and the importance of good inter-communal relations.

Muslims fear they will be the victims of a backlash

But as the European Union prepares to enact a range of new security measures, including a pan-European arrest warrant, pressure has also grown on local Islamic leaders to counter religious extremism and ensure that mosques are not being used as a meeting place for those planning organised violence.

Zacarias Massaoui, who was arrested as a suspect in the US hijack attacks, regularly attended a mosque in north London. So did two others suspected of planning attacks on US Embassies in Europe.

Islamophobia

The Islamic Council of Britain has condemned the attacks on the US but also warned that the ongoing air strikes will lead to "further polarisation in the world."

Many British Muslims, especially young men, have grown more radical in response to high tensions in the Middle East and what they see as "Islamophobia" in Britain.

The government is seriously worried about this trend: in Britain 16 Islamic organisations considered dangerous have been banned.

Germany has identified 12 extremist Muslim groups with more than 3,000 members. Germany has more than three million Muslims, mostly Turks who are still described as "foreigners" because they do not have German nationality, even though they were born there.

Suspects linked to the US attacks have been rounded up across Europe

France - which suffered a spate of bombings in Paris in the mid-1990s blamed on the Algerian-based Armed Islamic Group (GIA) - has more than four million Muslims, many of North African descent.

In France and Germany opinion polls show the most Muslims deplore the hijack attacks on the US.

But the response of Islamic leaders is complicated by the alienation of many Muslims who have been denied settled immigrant status or want to assert their own religious and cultural identity.

There have been many complaints of police harassment and other abuses.

Shaky consensus

In France, an opinion poll showed that 90% of Muslims there condemned the terrorist attacks in the US.

But 68% also expressed understanding that American policy in the Middle East "might push Islamic extremists to the limit."

The rector of the Paris Mosque, Dalil Boubekeur, was quoted as saying that an escalation of the military operation could shatter the "silent consensus" within the Muslim community.

However, as in the US, a new shadow of public suspicion may to fall on Muslims because, by definition, members of al-Qaeda or similar groups must be followers of Islam.

France suffered a wave of attacks by Algerian extremists

The decline in tolerance is shown by one recent opinion poll in the Netherlands. It found that more than 60% of Dutch people now agreed with the idea that Muslim immigrants who supported the hijacking attacks in the US should be deported.

Europe's political leaders say they are seeking understanding and co-operation from Muslim community leaders.

They need it to win the battle against terrorism at home. But to build it a lot remains to be done.