STOCKHOLM (AP): The European Union on Friday summoned Iranian ambassadors across the 27-nation bloc in a joint protest against the detentions of staff at the British Embassy in Tehran.

A top Iranian cleric had said earlier Friday that some of the detained embassy staffers would be put on trial, and accused Britain of playing a role in instigating widespread protests that erupted over the country's disputed presidential election.

Britain proposed recalling all EU ambassadors from Tehran in a sign of unity, but the bloc opted for gradually increasing pressure on the Iranian regime, Swedish Foreign Minister Carl Bildt said.

He said the EU's ``escalatory approach to Iran was working,'' and noted in a statement that seven of nine embassy employees had been released.

In London, Foreign Secretary David Miliband said Britain is ``deeply concerned'' about the two staff members who remain in Iranian detention.

Britain is ``confident that our staff have not engaged in any improper or illegal behavior,'' Miliband said in a statement, adding that the ministry was seeking urgent clarification from Iranian authorities and that he would speak with Iranian Foreign Minister Manouchehr Mottaki about the issue.

The European Union plans to review the situation next week, unless the remaining staffers are released, said Bildt, whose country holds the rotating EU presidency. He said he was awaiting confirmation of reports that Iran would put some of the detained staffers on trial.

Governments across Europe confirmed they were summoning Iranian ambassadors to demand the release of the remaining detainees. ``If this doesn't happen, the EU will take further measures,'' Sweden's Foreign Ministry said, without specifying what the next step would be.

The German Foreign Ministry said the arrests violated ``diplomatic customs and are aimed not only at Great Britain but all the EU.''

French President Nicolas Sarkozy indicated he supported the British request to turn up the heat on the Iranian regime.

``France has always wanted to strengthen the sanctions, so that Iranian leaders will really understand that the path that they have chosen will be a dead end,'' he said in a joint news conference with Swedish Prime Minister Fredrik Reinfeldt. ``Now it's up to the British to tell us what they need, what help they need.''

Sarkozy said that ``our solidarity with our English friends is total.''

The issue poses a difficult challenge for the EU. Recalling diplomats from Tehran would be an extraordinary move and a powerful signal of unity in the wake of Tehran's postelection crackdown.

But punishing the regime too harshly also risks spoiling chances of making headway on the critical issue of Iran's disputed nuclear program.

Sweden is calling for a moderate response to the Iranian crackdown on protesters to avoid pushing Iran further into isolation.

``It's a cry for freedom, a type of reaction which mustn't transform into turning into a conflict between Iran and the rest of the world,'' Reinfeldt said.