The video clip, provided to Amnesty International, the human rights group, was allegedly shot on July 19 and purports to show three men being hanged in Azadi Square in the city of Kermanshah. The trio had been convicted of rape.

During the clip, the three stand on top of buses as guards fix ropes round their necks that are attached to a bridge overhead, in front of an audience. The crimes are announced over a loudspeak and then the buses drive away. The video cuts out before the men are left hanging.

"These latest public executions underline the continuing horror of the death penalty in Iran," said. Amnesty International Middle East and North Africa Deputy Director Hassiba Hadj Sahraoui.

"Not only those executed, but all those who watch public executions, including, children, are brutalised and degraded by the experience. These public displays of killing perpetuate a culture of acceptance of violence and bloodlust, rather than a belief in justice.

"We have also been informed that the arrest, trial and execution of these men took barely two months, which raises serious questions about the fairness of the trial."