Foreign Secretary David Miliband has insisted that Britain is not seeking "regime change" in Iran in the wake of the country's disputed presidential elections.
Mr Miliband rejected charges by Iran's Supreme Leader Ayatollah Ali Khamenei that Britain had been responsible for fomenting unrest after hard-line president Mahmoud Ahmadinejad was controversially declared the victor.
He said that the Islamic regime was now facing a "crisis of credibility" among its own people.
"Regimes often want to hide behind the idea that they are facing a massive foreign offensive. In truth, they're not," the Foreign Secretary told Sky News.
"No-one is seeking regime change in Iran from the outside world. It is for the Iranians to choose their own government and the demonisation of America and the West has been staple of the regime for 30 years."
He told the BBC: "The truth is that there is a crisis of credibility between the Iranian government and their own people. It is not a crisis between Iran and America or Iran and Britain, however much the Iranian government want to suggest that.
"The people on the streets are there because of the crisis of credibility of the election results that were announced. That is not a British motivation, that is an issue for the Iranian people to decide."
Earlier this week the Iranians expelled two British diplomats, accusing them of spying, prompting the tit-for-tat expulsion of two Iranian diplomats from the embassy in London.
Mr Miliband confirmed that the British embassy was in touch with the Iranian authorities about a journalist with dual British and Greek nationality who was arrested last week.
Washington Times reporter Iason Athanasiadis-Fowden, known as Jason Fowden, was detained as he was attempting to leave the country according to the Iranian news agency IRNA. Mr Miliband said that the Greek government was taking the lead on the case as Mr Fowden had been travelling on a Greek passport.
