Former Iranian nuclear negotiator Hossein Mousavian has been acquitted of spying charges by an Iranian court, but found guilty of a propaganda charge.
It is not known what sentence Mousavian will now face
A judiciary spokesman said Mousavian had been facing three charges: "Spying, keeping confidential documents and propagating against the ruling system."
He was found not guilty of the first two but found guilty of the third, Ali Reza Jamshidi told reporters.
President Mahmoud Ahmadinejad had dubbed Mousavian a "spy" and "traitor".
Earlier this month that Mousavian was charged with giving classified information to the British embassy.
Mr Jamshidi did not say what kind of sentence Mousavian, who was detained and bailed in May, would face.
Mousavian was a deputy of Hasan Rowhani, the top nuclear negotiator under the reformist ex-president Mohammad Khatami.
He is close to former President Hashemi Rafsanjani, a leading rival to President Mahmoud Ahmadinejad.
In October, chief nuclear negotiator Ali Larijani resigned over reported differences with the president on the nuclear issue.
That was widely seen as a case of Mr Ahmadinejad tightening his hold on key posts in the Iranian administration.
Mr Ahmadinejad has denounced critics of his policies as traitors
Correspondents say the president wants to remove opponents of his economic and foreign policies, which have come under increasing criticism within Iran in recent months.
Reformists and several senior clerics have particularly criticised Mr Ahmadinejad's nuclear policy, warning that it has seriously jeopardised the country.
The UN Security Council has imposed sanctions on Iran because of fears it is seeking to develop nuclear weapons, while the US has not ruled out military action.
This month Mr Ahmadinejad denounced as "traitors" those in Iran who have criticised its nuclear programme, state media reported.