Students attending a debate about sharia law were told they would be "hunted down and killed" by a man who burst into their lecture theatre and filmed them on his phone.

A man in a dark hooded top said he knew the identities of the 40 guests present and knew where they lived, before claiming that they would be tracked down if anything negative was uttered about the Prophet Muhammad.

The incident took place on Monday evening at a meeting organised by the Atheism, Secularism and Humanism Society at Queen Mary University in London.

The society’s president, Jen Hardy, said when the man left the room, two members of the audience applauded.

“The same man then began filming the faces of Society members in the foyer and threatening to hunt them down if anything was said about Muhammad, he added that he knew where they lived and would murder them and their families,” she said.

“On leaving the building, he joined a large group of men, seemingly there to support him. We were told by security to stay in the Lecture Theatre for our own safety.”

The meeting, where Secular Europe Campaign supporter Anne Marie Waters was due to give a speech, was cancelled.

“This is the first time this has happened, it’s really very frightening and you don’t know what else it’s going to turn into,” she said.

“I’m not worried about repercussions, but I’m worried about it happening again.”

Andrew Copson, Chief Executive of the British Humanist Association condemned the “shocking” intimidation, saying: “Free expression, the free exchange of ideas and free debate are hallmarks of an open society; violence and the threat of violence should never be allowed to compromise that, especially in our universities.”

Queen Mary Students’ Union said: “Our students’ safety is of absolute priority and we take such reports very seriously. We are confident our processes have been followed in organising the event and will be supportive of any investigations carried out by the Police or Queen Mary, University of London.”