European Union nations have summoned Iranian ambassadors to protest the detention of British Embassy staff in Tehran.
Officials say EU members agreed to the move Friday at a meeting in Brussels.
EU officials are considering additional measures including visa bans on Iranian officials.
A top Iranian cleric Friday said that some British Embassy staff will be put on trial for allegedly playing a role in post-election demonstrations. Ayatollah Ahmad Jannati said during a prayer sermon that some embassy employees confessed to instigating unrest. Jannati is close to Iran's supreme leader.
Nine British Embassy staffers were arrested in Tehran last Sunday. Some were freed, but the British government says two are still in custody.
Britain's foreign office expressed concern Friday and said it is investigating reports that the employees face trial.
Some information for this report was provided by AP, AFP and Reuters.