The British Broadcasting Corporation and RFE/RL say the Iranian regime has been threatening the Iranian families of people who work for their Persian-language services.
The BBC said Iranian intelligence agents had warned the families of 15 Persian Service staff that they must stop working for the BBC or their lives in London would be endangered.
Liliane Landor, head of languages services at the BBC World Service, said "the harassment has included threats that relatives will lose jobs and pensions” and be prevented from leaving Iran to travel abroad.
RFE/RL Radio Farda director Armand Mostofi said, "The harassment has intensified in the past several weeks, as the authorities take all possible precautions against anything that may challenge their control over the elections."
Iran is holding a presidential election on June 14.