Brown hasn't spoken to Putin since his first day at No10

The Foreign Office is said to be alarmed at the lack of contact between the two leaders, which has fallen to levels last seen in the pre-glasnost era of Margaret Thatcher and Leonid Brezhnev.

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Diplomatic sources say that the first – and last – direct contact between the men was on June 27 last year, when the Russian leader rang Mr Brown to congratulate him on succeeding Tony Blair.

Subsequent attempts to bridge the gap had, they said, been blocked by a "stubborn" Downing Street.

Putin will hand over power on May 7 to Dmitry Medvedev, widely seen as a "puppet" who will allow his predecessor to keep hold of the reins of government.

Putin is poised to become Russia's Prime Minister, enabling him to micro-manage the economy – and influence Britain's lucrative interests in his country's oil and gas sector.

Relations between London and Moscow deteriorated drastically after the murder in 2006 of exiled Alexander Litvinenko and Russia's refusal to British demands for the extradition of chief suspect Andrei Lugovoy.

Tit-for-tat diplomatic expulsions and the closure of the British Council's centre in St Petersburg followed.

"Brown should have spoken to Putin," a Russian source said last night. "The real power will remain with Putin and there can be no repair in relations between our countries without the main man being involved.

"The current silence is the worst since the Soviet old guard of Brezhnev, Andropov and Chernenko were in the Kremlin."

British diplomats are concerned about our relationship with Russia because the soaring value of its natural resources have made it a superpower again – and one in which key government positions are occupied by Putin's former colleagues in the KGB.

"Part of the problem is that Brown does not have Blair's charm or his ability to defuse difficult situations," a British diplomatic source said.

"Also, he is not particularly interested in foreign affairs, or at least not the traditional power balances."

Brown's frosty stance is in stark contrast to the regular telephone diplomacy between Putin and Blair, with the pair bantering away on first-name terms.

Downing Street said: "We don't comment on the Prime Minister's private conversations. But he has written to Mr Medvedev."