Britain sparked controversy yesterday by sending its second most senior diplomat in Tehran to the ceremony at which Ayatollah Ali Khamenei, the Supreme Leader, officially endorsed President Ahmadinejad’s hotly disputed re-election. Iran’s opposition leaders, who say the election was rigged, boycotted the event.

The Foreign and Commonwealth Office (FCO) sent Patrick Davies, the British Embassy’s deputy head of mission, even though the regime has repeatedly accused Britain of fomenting the turmoil that has engulfed Iran since the ballot, arrested Iranians working for the Embassy and expelled the BBC’s Tehran correspondent.

The FCO said that it sent Mr Davies to the ceremony instead of Simon Gass, the Ambassador, to show there was no “business as usual” with a regime accused of rigging the election, brutally suppressing the opposition and staging show trials of dissidents.

The FCO also argued that it had to keep talking to the regime about its nuclear programme, human rights and other pressing issues, and that “to do this, communication channels have to be open”.

It said it was practising “hard-headed diplomacy”, but domestic critics said the FCO was in danger of legitimising the regime.

William Hague, the Shadow Foreign Secretary, said: "Under all the circumstances, representation at this event should have been kept at the minimum level possible. Other countries seem to have done that more effectively than the Foreign Office.”

Sir Menzies Campbell, the former Liberal Democrat leader and member of the Foreign Affairs Committee, said the decision was bizarre. "The Government has been vociferous on behalf of human rights and individual freedoms in Iran but at a time when a show trial is taking place it surely would have been prudent to preserve coolness and meet only the most perfunctory diplomatic niceties."

Alireza Nourizadeh, director of London’s Centre for Arab and Iranian Studies, said Britain should have taken a stand by sending nobody, and that its decision would have disheartened the thousands of Iranians who risk their lives by demonstrating against the regime. “I am really shocked... It was a sort of recognition of Ahmadinejad,” he said.

European Union member states failed to agree a common stand. Sweden, which holds the EU’s rotating presidency, sent its Ambassador to represent the EU. France and Italy, one of Iran’s biggest trading partners, sent their second-ranking diplomats, but Germany sent one of its lowest-level diplomats.

The FCO has not decided whom to send to Mr Ahmadinejad’s swearing-in before the Iranian parliament on Wednesday.

Ayatollah Khamenei told yesterday’s ceremony that the election was a “glorious page” in Iran’s history, but the event exposed the huge rifts the controversial ballot and its ugly aftermath have caused within the country.

It was boycotted by Mir Hossein Mousavi and Mehdi Karoubi, the defeated candidates, and by the former presidents Mohammed Khatami and Ali Akbar Hashemi Rafsanjani. They have denounced the election as a charade and condemned the subsequent crackdown. Also absent were any members of the family of Ayatollah Ruhollah Khomeini, the leader of the revolution in 1979.

The ceremony was also notable for an awkward embrace between Ayatollah Khamenei and Mr Ahmadinejad that appeared to point up the tensions that have emerged between the pair since Mr Ahmadinejad defied the Supreme Leader and enraged hardliners by choosing his son’s father-in-law as his deputy.

State television showed Ayatollah Khamenei apparently preventing Mr Ahmadinejad from kissing his hand to show his loyalty as he did during the same ceremony in 2005. The President ended up clumsily kissing the robe on Ayatollah Khamenei’s shoulder.

Ayatollah Khamenei and Mr Ahmadinejad both used the ceremony to portray the election as a triumph over foreign enemies bent on destroying the Islamic Republic.

Mr Khamenei said Iran had voted “in favour of a fight against arrogance and brave resistance to the international domination-seekers”.

Mr Ahmadinejad told the West: "Gone is the era of bullying. You can no longer impose your will on the world nations. I recommend you turn back to the path of justice and shy away from meddling in other's affairs...The noble Iranian nation will not brook such insincerity and selfishness."

The security forces had to flood on to the streets to prevent further demonstrations yesterday, and seven weeks after the election they are still struggling to suppress the opposition and prevent mass protests. The opposition is calling for a million Iranians to take to the streets of Tehran tomorrow when Mr Ahmadinejad is sworn in.

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