Exiled Iranians are seeking the arrest of Gholamreza Mansouri, a judge and former prosecutor at the country’s notorious Evin prison, after his surprise appearance in Europe for medical treatment.
Kaveh Moussavi, a human rights lawyer living in exile in Britain, said prosecutors in Germany had “no choice but to arrest him”.
Those campaigning for his arrest say Mr Mansouri was the judge who ordered the arrest and oversaw torture of at least 20 journalists in Tehran during his tenure overseeing the country’s press court.
Mr Mousavi claimed that Mr Mansouri was also complicit in crimes including assassinations and hostage taking.
Mr Mansouri is believed to at a medical clinic in Hanover run by a surgeon of Iranian origin.
News of his presence there led protesters to gather outside the clinic in northern Germany calling for his arrest.
The top Iranian judge made a video statement saying he had gone abroad to an unspecified destination for treatment and would go to an embassy of the Islamic Republic for help in finding a way home.
Mr Moussavi said he would initiate legal proceedings in Germany, Sweden and Norway against the former Evin prosecutor.