Protestors marred an abortion debate at an Oxford college last night as police were called to break up violence.

An Irish abortion debate organised by the group Oxford Students for Life was interrupted by pro-abortion campaigners at St John's College. 

The university student group said pro-choice campaigners chanted continuously for 40 minutes while Irish Times columnist Breda O'Brien attempted to give her presentation.

A message on the group's Facebook page read: "College security attempted to intervene and an altercation between one student and college security officer occurred.

"The OSFL committee called for calm and asked that no students be removed, but eventually the college security decided to call the police.

"Throughout, the people sincerely attending our event conducted themselves with immense and impressive dignity."

Thames Valley Police confirmed officers were called to the college following reports that a protest had become 'disruptive'.

Police spokesman Jack Abell said: "Officers attended the scene and spoke with protestors, who later left the premises peacefully. No arrests were made."