Cambridge University's Students' Union said it is "alarmed" by claims that police 'tried to spy' on its members.
The Guardian newspaper has obtained a video of an officer trying to recruit an informant to target protest groups.
The Students' Union said it "condemned" the action and wants the government to look at how UK security forces use surveillance.
The National Union of Students (NUS) described it as "an absolute scandal".
The NUS said it undermines students' right to protest and demands to know just how widespread the practice is.
More top news
A medical examiner concluded that an accidental overdose had caused Tom Petty to suffer a fatal heart attack at his Malibu home in October.
One year on from his inauguration, Donald Trump's supporters are even more passionate about him and his cause than before he entered office.
Support for new parents has faced deep cuts in recent years - and some social workers warn it could lead to a rise in forced adoption.