A report by the semi-official Mehr news agency said the individuals had done reporting for the BBC and helped the corporation train Iranian journalists but did not name the people detained nor say how many had been arrested.
It quoted an unnamed official as saying the group had been active in Iran since 2009.
The BBC said in a statement that the report “should be of deep concern to all those who believe in a free and independent media” but added it had “no BBC Persian staff members or stringers working inside Iran.”
In October, Iran released two filmmakers who were in jail on similar charges.
Tehran has accused the BBC of operating as a cover for British intelligence and of hosting Iranian dissidents.