The government has pledged to reassess its Prevent counter-terrorism strategy to investigate whether it has done enough to challenge extremists.

Universities Minister David Willetts admitted there might still be cases where extreme speakers have fostered hatred or violence.

Millions of pounds have already been spent on the project in an attempt to prevent Muslim radicalisation.

Mr Willetts said: "Over the coming months the government will be looking in detail at the Prevent strategy to ensure it is properly focused and, as part of this, we will look at the challenge to our liberal values from extremists and their messages."

He made his remarks in the wake of a new comprehensive list of extremist speakers who have appeared on British university campuses, compiled by the Centre for Social Cohesion thinktank. Concerns over preachers have been raised repeatedly over the past six months.

The problem came to the fore following the arrest last December of former University College London student and Islamic Society president, Umar Farouk Abdulmutallab, on suspicion of attempting to blow up a transatlantic jet. He is awaiting trial in the US.

CSC's report highlights the involvement of dozens of former students and campus speakers in terror plots, suspected Islamism-inspired offences and radicalisation while at British universities.

It records appearances of extreme speakers invited by Islam Societies and other student union groups at 12 London universities, as well as campuses in Northumbria and Birmingham.

Among the preachers listed are:

● Anwar al-Awlaki, a radical pro-al-Qaeda preacher believed to be on the run in Yemen and regularly invited to address students by video link. He encourages Muslims to join the jihadi fight and has been linked to the 9/11 terror attacks and last year's attempted plane bombing.

● Sheikh Riyadh ul-Haq, who has previously spoken at UCL. He has made antisemitic comments, saying Jews are "all the same. They've monopolised everything: the Holocaust, God, money… the media".

● Ismail Patel, who was invited to speak at SOAS. Chairman of the Friends of Al Aqsa group, he was on board the Mavi Marmara ship which was part of May's flotilla to Gaza. He has previously saluted Hamas for "standing up to Israel".

The report states: "Though concern over this issue is growing, our warnings have been repeatedly ignored by political leaders, university heads and national student bodies. All have been in a position to stop this hate. All have failed."

Hannah Stuart, CSC researcher, said: "There are people in this report who should never be allowed to speak on campuses. They go so far as to glorify terror. Enough is enough."

In 2006, a report by the All-Party Inquiry Into Antisemitism warned of the threat posed by extreme speakers and said the response of vice-chancellors was "at best patchy".

Denis MacShane MP, who chaired that inquiry, said: "Vice-chancellors largely remain in denial and confuse legitimate criticism of Israel with the demonisation and delegitimisation of the Jewish state and Jewish people.

"They keep the BNP and extreme right at arm's length but have a double standard when it comes to ultra-jihadi hatred of Jews and Israel."

Dr MacShane added that Prime Minister David Cameron should make Education Secretary Michael Gove responsible for combating antisemitism on campus.

"This issue is too important to be left in the do-nothing hands of the Department of Business," he said.

But the National Union of Students criticised CSC, saying the report was "likely to instil fear, increase tensions between students, and encourage Islamophobia on campus".

Universities UK has set up a working group to tackle the issue, but is not expected to report on its findings or possible solutions until later this year.