Police arrived to seize the pair – members of the F*** for Forests group – after one shocked churchgoer dialed 999.
Other furious parishioners pulled the couple apart and held them until police arrived, and also grabbed a man that had been taking pictures of the act.
A police spokesman confirmed: "We arrested three people for sexual activity in front of the altar in Oslo Cathedral."
A spokesman for the trio – who have not been identified by police – said: "We had to pay a small fine or spend 16 days in jail. We chose the former because we didn't want to spend so long without having sex."
Swedish pressure group F*** For Forests is trying to publicise global deforestation by having sex in public to draw attention to the problem.
It believes in campaigning for the cause by outraging public decency.
Post published in: News