By Alex Stevenson
Iran's ambassadors are being summoned by member states across the European Union, it has emerged, in what is being viewed as a major victory for the Foreign Office.
The development is the latest escalation of an ongoing diplomatic crisis between Britain and Iran after nine UK-employed diplomats were arrested last weekend.
Earlier today reports emerged that Tehran was considering trying the two staff still yet to be released.
The AFP news agency cited Iran's Guardian Council, a senior body of jurists and theologians appointed by the Supreme Leader, saying a trial may be taken against those accused.
An EU diplomat confirmed agreement had been reached yesterday that countries across the EU, 19 of which have embassies in Tehran, would stand united against Iran.
Ambassadors across the EU will hear protests against the unfair treatment of the British embassy diplomats.
"The UK is very happy with the EU actions thus far. The clear solidarity the EU has shown has had an effect," a Foreign Office spokesperson said.
"With seven out of nine detained staff now released the EU has been clear it stands together on this issue: action against one EU member state is action against all."
Sources inside the Foreign Office had made clear achieving EU unity on this issue seemed unlikely.
But Britain's achievement in doing so means Iran faces further pressure to release the two diplomatic staff.
Further united EU actions now become possible, including the much more serious step of withdrawing ambassadors from Tehran.