The rally on Wednesday night, organised by the anti-abortion group Life, was interrupted by students and members of the Socialist Workers Party.

Banners were torn down and there were minor scuffles.

Police had to be called to keep the two sides apart.

The Life rally has been an annual event for 15 years and they had planned a candle-lit march to mark 32 years since the abortion act became law.

Rosaleen Doyle: "incredibly disturbed"

The action by the Socialist Workers' Party follows revelations on Newsnight Scotland that a militant anti-abortion group called Precious Life were planning to start campaigning in Scotland.

Rosaleen Doyle of the SWP said: "I've been following this organisations progress, Precious Life's progress in news reports.

"I'm incredibly disturbed at some of their antics and the strategies they've been employing in other parts of the country.

"I felt it was really important that, where they show their faces, we should be here."

Robert Graham of Life said: "In a democratic society, this is a perfectly permissible activity.

"Are we going to get to the stage where the only cause which is not allowed to be aired is going to be the pro-life cause?"

The Life rally ended with a private church service.

Precious Life is planning to launch in three weeks' time.