Human rights campaigners on Thursday paid tribute to an Iranian activist who killed himself hours after warning he would do so if four inmates seen to be political prisoners were not freed.

Iranian journalist and human rights activist Kianoosh Sanjari died by suicide in Tehran on Wednesday, in protest against what he called the country's repressive regime Mr Sanjari, who was 42, had threatened in a social media post on Tuesday to take his own life if four political prisoners were not released by Wednesday evening.