A late report yesterday by Kaleme.Com says judiciary officers detained Bahman Daroshafaei on Wednesday morning in his residence did not elaborate on the reason.
Daroshafaei, who left the BBC Persian service in London about two years ago, was working as translator of political books and novels.
The detention took place as Iran's Foreign Minister Mohammad Javad Zarif arrived in London today to participate in a meeting on Syria.
Calls to judiciary officials were not immediately returned today, part of the weekend in Iran.
The move is part of a crackdown on journalists and activists by hard-liners ahead of highly anticipated parliamentary elections scheduled for later this month.