Ayatollah Ahmad Jannati, the head of the influential Guardian Council and an ally of Iran's supreme leader, Ayatollah Ali Khamenei, told worshipers at Friday Prayers in Tehran that the local employees would be tried after they "made confessions."
Ayatollah Jannati did not say how many of the British detainees would be tried or what charges they would face, news reports said.
Iranian officials have previously accused the British staffers of encouraging protests.
In response to the news of possible charges, European governments are threatening to pull out their ambassadors from Iran. Some fear that would tie the hands of Western nations if things worsen.