Iran's media has claimed authorities have arrested a spy working for British intelligence agency MI6.
The semi-official ISNA news agency said today the man, who has not been identified, was arrested in the southeastern Iranian town of Kerman after authorities spent months tracking him down.
A Kerman judiciary official, who was not named by the news agency, said the man had exchanged information with four British intelligence operatives. The report alleged he is currently standing trial and has confessed to the charges.
The man is believed to be aged over 50 and with an "academic education", according to Iran's conservative news agency Tasnim, fluent in English and without any official post. The agency said he was arrested after ten months of spying.
The UK foreign office has said it does not comment on intelligence matters, according to the BBC.
It has not been suggested that the alleged spy is a Briton, and Tehran has a history of announcing the arrest of people it claims are spying without releasing further details.
The arrest comes as Iran and Britain are repairing ties following the election of moderate President Hassan Rouhani in June. The British Embassy in Tehran was shut down in 2011 after hardliners overran the building.
In a separate case an investigation undertaken by the Associated Press has claimed an American who vanished seven years ago in Iran was working on an unauthorised CIA mission at the time of his disappearance.
Officials believe Robert Levinson is being kept in Iran, but the country denies there is evidence he is being held hostage there.