Al Qaeda-inspired militants pose a serious threat at some universities and students should be told of the dangers, the government said on Tuesday.

"Higher education institutions and student leaders have an important role in educating their students about how violent extremist groups operate and recruit and who they target," it said in published guidance to universities and colleges.

It said they should set up support networks so that students who felt concerned or at risk could ring a confidential helpline or talk to a tutor or adviser.

"The threat from terrorism in the UK is real. Although it is not widespread, there is evidence of serious extremist activity in higher education institutions," universities minister Bill Rammell said.

Students have featured in several high-profile British terrorism trials, but the government's previous efforts to tackle campus militants have provoked controversy.

The University and College Union (UCU), which represents lecturers, rejected guidance issued by ministers in 2006, saying academics would not spy on their students.

Rammell denied that was the government's intention. He said universities were arenas for free speech and debate, but they should also use their judgment to distinguish between legitimate radical views and illegal incitement.

"There is a line at which you move from analysis and understanding towards outright advocacy of violent extremism, and it's that that we're concerned about," he told reporters.

UCU leader Sally Hunt said the union welcomed the government's greater emphasis on community cohesion but added: "Staff are not trained to, and should not be expected to, police their students."

UNDERGROUND

She said it was worrying that the guidelines specifically targeted the Muslim community.

The National Union of Students said aspects of the proposals were baffling and they could damage relationships between lecturers and students.

The government paper reiterates some earlier guidance; for example, that universities should not allow external speakers with a record of promoting "violent extremism".

Rammell declined to be drawn on the number of British universities he believed at risk from militant activity. He said there were signs some groups had sought to "take their activities underground" in response to publicity over the issue.

Anthony Glees, a British academic who published a study on student militants in 2005, said none of Britain's 120-plus higher education establishments was immune.

"It can happen anywhere. Nobody can take their eye off the ball," said Glees, a security and intelligence expert at Brunel University in west London.

Among recent British cases, a Scottish student was jailed for eight years last October for possessing and distributing terrorist material via the Internet.

Last July, a court convicted a schoolboy and four students from Bradford University in northern England who had planned to travel to Pakistan for militant training in order to fight Western forces in Afghanistan.