Britain and Iran moved towards a full-blown diplomatic crisis today as David Miliband rejected claims that the Government was stirring protests against the disputed re-election of president Mahmoud Ahmadinejad.

Within hours of confirmation that the BBC correspondent Jon Leyn had been ordered to leave Tehran, Iran’s foreign minister rebuked Britain for raising questions about voting irregularities.

As the death toll from clashes between demonstrators and security forces continued to rise, Manouchehr Mottaki told diplomats: “Great Britain has plotted against the presidential election for more than two years. We witnessed an influx of people before the election. Elements linked to the British secret service were flying in in droves.”

His comments come after Iran’s supreme leader Ayatollah Ali Khamenei accused “the evil British government” on Friday of interfering last weekend's election.

But Mr Miliband suggested that Mr Mottaki was seeking to distract attention from the country’s internal difficulties.

“Foreign Minister Mottaki’s attempt... to turn the dispute among Iranians about the election results into a battle between Iran and other countries - the UK in particular - is without foundation,” he said.

“I reject categorically the idea that the protesters in Iran are manipulated or motivated by foreign countries. The UK is categorical that it is for the Iranian people to choose their government, and for the Iranian authorities to ensure the fairness of the result and the protection of their own people.

“I therefore deplore the continuing violence against those seeking to exercise their right of expression. This can only damage Iran’s standing in the eyes of the world. The blame being heaped on foreigners is no excuse.”

Mr Miliband added that the growing death toll from clashes between demonstrators and security forces in Tehran would “raise the level of concern” around the world.

Iranian state media today reported the deaths of 13 more demonstrators in what has been the country’s most serious internal conflict since the 1979 Islamic Revolution. It brought the official death toll for a week of unrest to at least 20.

The 13 who died yesterday in clashes with black-clad police wielding truncheons, tear gas and water cannons were dubbed “terrorists” by a state broadcaster. Thousands of demonstrators assembled in Enghelab Square in the heart of the capital, according to witnesses, and a suicide bomber also struck a key regime monument - the mausoleum of revolutionary leader Ayatollah Ruhollah Khomeini in south Tehran - killing himself and wounding three people.

But the violence was condemnded by world leaders. Last night Barack Obama, who is trying to balance a desire for long-term diplomacy with calls for strong rhetoric, made his most striking comments since the crisis began.

Mr Obama, who has appealed for dialogue with Tehran after three decades of severed ties, again called on the Iranian government to stop “all violent and unjust actions against its own people”.

“The Iranian government must understand that the world is watching," he added.

Iran’s most senior dissident cleric, Grand Ayatollah Hossein Ali Montazeri, has called for three days of national mourning for those killed in the protests.

Meanwhile Iran has warned the British media of further action if it continues to “interfere” in the country's affairs.

“If various British radio and television networks continue to interfere in our country’s domestic affairs by broadcasting fake and incorrect reports of Iran or ignoring international journalism ethics, there will be more stern action taken,” the ministry of culture and Islamic guidance said.

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