State television in Iran says that two people have been killed and two others injured by an explosion at an Islamic revolutionary court in the capital, Teheran.

It described the victims as martyrs, and said the cause of the blast was being investigated.

Initial reports from the Iranian news agency said itwas an accident, caused by the mishandling of explosives being used as evidence in a court case.

But eye-witnesses said that an unidentified man was seen entering the court building with a briefcase shortly before the explosion.

One report spoke of up to sixty casualties.

Later, an Iranian opposition group, Mujadehin Khalq, issued a statement saying it was responsible for the blast.