Sources inside Iran told the BBC several people have been detained for alleged links to the British broadcaster's Persian news service.
The action follows charges Iranian authorities are conducting a campaign of bullying and harassment against people working for the Persian service, the BBC reported Tuesday.
The sources said any cooperation with the BBC's Persian service is illegal and would be prosecuted.
The BBC has said no BBC Persian staff members or stringers are currently working inside Iran.
Last week, BBC Director General Mark Thompson wrote Iran was using "disturbing new tactics," including the targeting of family members of Persian service staff working outside Iran.
Thompson revealed the sister of one man had been arrested and held on unspecified charges at Evin Prison in Tehran.
Some staff said their Facebook and e-mail accounts were hacked and they were subjected to a "stream of false and slanderous accusations," he said.