Britain will call for stronger economic sanctions on Iran at a meeting of European Union foreign ministers in Brussels today after the storming of its embassy in Tehran, according to Foreign Secretary William Hague.
"I will be advocating an intensification of economic sanctions on Iran, particularly to increase the isolation of the Iranian financial sector," he told BBC radio from Brussels.
"I stress that the measures I hope we will agree today are related to the Iranian nuclear programme, these are not measures in reaction to what has happened to our embassy," he added.
Britain shut Iran's embassy in London and expelled all its staff on Wednesday, saying the storming of the British mission in Tehran on Tuesday could not have taken place without consent from Iranian authorities.
"Our bigger, long-term concern is the Iranian nuclear programme, the danger that poses to the peace of the Middle East and the wider world ... and it is for that reason that we will agree, I hope, today to intensify European Union sanctions on Iran," Hague said.
EU foreign ministers meet in Brussels later on Thursday to map out Europe's response to a report by the International Atomic Energy Agency in recent weeks that suggested Iran has worked on designing an atom bomb.
The latest escalation of already-terse relations between the UK and Iran came after the UK severed all financial ties with Iranian banks in response to mounting fears over the country's nuclear ambitions.
It was part of a wider international effort by the United States and Canada to put pressure on the Islamic republic after the latest expert assessment increased fears the regime was seeking nuclear weapons.
Iran responded by passing legislation downgrading diplomatic ties with Britain, which was swiftly followed by the internationally-condemned attack on the embassy.
The Iranian Foreign Minister has apologised for the incident.
But Mr Hague told MPs on Wednesday: "No difficulty in relations can ever excuse in any way or under any circumstances the failure to protect diplomatic staff and diplomatic premises."