The government's strategy to tackle extremism on campus pushes officers into the role of "thought police", according to a constable overseeing the policy in London universities.
PC Mark Davis told a group of university representatives that he was not "overly comfortable" with a review of the Prevent strategy in June, which widened its scope to cover "extremism" as well as "violent extremism".
Speaking at the Association of University Administrators' conference in London last week, PC Davis said that the switch in policy was something that his "bosses within the police are trying to work out with the government because it really puts us into the realm of thought police".
He added: "It's not something that I'm overly comfortable [with]. Anyone can be extreme. Police officers can be extreme in their views - we want more pay, we can be extreme about that."
He said that "we're trying as best we can to stick to people who are willing to take that extra step from extreme views [to violence]".
The officer told AUA members that they should consider contacting his team if they found students handing out extremist literature, organising off-campus meetings or exhibiting "sudden changes in behaviour".
The police were "very interested, and you should be very interested, in things like that", he said.
During his presentation, a slide was shown illustrating the different types of threat that Prevent addressed.
It included pictures of a hijacked plane exploding as it hit the World Trade Center in New York in the 9/11 attacks, the aftermath of an IRA bombing, an Animal Liberation Front militant, and a member of Fathers 4 Justice, which disbanded in 2006, dressed as Batman.
As well as covering actions inspired by al-Qaeda and Irish republicans, PC Davis said Prevent also dealt with the activities of animal rights groups, environmental activists and the far Right. But he stressed that his team was at pains not to tell students, "We want you to think in this particular way".
A spokesman for the Home Office said that Prevent "challenges extremist ideology and tackles the radicalisation of vulnerable people".
He added: "It is not about policing people's thoughts but challenging those extremist views that seek to legitimise terrorism."
The Home Office defines extremism as a "vocal or active opposition to fundamental British values". The Metropolitan Police said it was "fully supportive and committed to the revised Prevent strategy".