Iran's official IRNA news agency says Iran has indicted 15 people on charges of "spying" for the United States and Israel.
The report did not identify the suspects nor give any details of when they were arrested and under what circumstances.
Iranian officials have several times in the past announced the arrest of suspected spies for the United States but provided little information to substantiate the detentions or allegations.
The report comes with a war of words escalating and after Iran claimed to have captured a U.S. drone that entered Iranian airspace from neighboring Afghanistan. The Iranian government has accused the drone of being a "spy plane" and has refused to hand it back following a request from President Barack Obama.
Relations between Iran and Britain are meanwhile strained over nuclear-related sanctions, diplomatic expulsions, and a mob raid on the British Embassy in Tehran.
European states and the U.S. have recently stepped up sanctions aimed at convincing Iran to abandon sensitive nuclear activities, which have also prompted four rounds of UN sanctions and condemnation from the International Atomic Energy Agency (IAEA).
compiled from agency and RFE/RL reports