Hizb ut-Tahrir demonstrated outside the US embassy in London in 2007
The University of London has cancelled the appearance of a speaker from an Islamic group that opposes democracy and integration into British society.
A representative of Hizb ut-Tahrir was due to appear at Queen Mary college in east London to debate Sharia law in the modern world.
But the group was told it could not take part after students campaigned about its "blatantly aggressive" views.
The university's union said the debate organisers acted to avoid controversy.
Hizb ut-Tahrir has previously said "those who believe in democracy are Kafir" [unclean] and said it was "dangerous" for Muslims to integrate into British society.
A leaflet displayed on its website once urged Muslims to "kill [Jews] wherever you find them".
Hizb ut-Tahrir's UK spokesmen deny links to terrorism and say the group, which is a legal organisation in the UK, opposes violence.
The organisation rejects claims it condones suicide bombing.
The organisation's stated aim is a worldwide Islamic caliphate run under Sharia law.
It is banned in Germany and much of the Middle East.
Tony Blair said he wanted to ban the group after the 2005 London bombings, because it allegedly radicalises young British Muslims. But after two reviews this did not happen.
The Conservatives have pledged to prohibit it if they win the next election.
Shadow home secretary Chris Grayling said: "Within the UK it takes extreme care about how it words its propaganda.
"But anyone who doubts its true character should look at the website in Bangladesh, which talks about mobilising armed forces to eliminate the Jewish entity.
"We cannot allow such views free rein in our society."
When campaign group Student Rights heard about the talk it urged Queen Mary student union to cancel it.
The union then discussed the event with the student society that organised it.
A union spokesman said the society's members were adamant Hizb ut-Tahrir would not use the event to "espouse hateful views", but decided to find a new speaker to avoid controversy.
But a spokesman for Student Rights said: "Hizb ut-Tahrir speakers have been known to condone suicide bombings and support Islamist movements which undertake terrorist acts such as Islamic Jihad.
"This can be frightening and intimidating for the student body."
He added: "On university campuses it is simply incomprehensible how such blatantly aggressive organisations can be invited to speak."
A Hizb ut-Tahrir spokesman said: "By lobbying to stop this week's event those organisations seem to believe their inability to effectively counter our arguments gives them the right to stop others debating with us.
"Their actions only prove how empty their rhetoric on free speech and human rights is."
A 2008 report by the Centre for Social Cohesion highlighted Queen Mary, University of London, as a place with a problem of Muslim extremism.
The controversy comes after a talk at University College London by radical preacher Abu Usamah was cancelled.
Usamah, who was recorded by Channel 4 saying gay people should be "thrown off a mountain", was prevented from speaking after a campaign led by human rights campaigner Peter Tatchell.