Russia played a trump card in its strategic poker game with the West yesterday by threatening to suspend an agreement allowing Nato to take supplies and equipment to Afghanistan through Russia and Central Asia.

The agreement was struck at a Nato summit in April to provide an alternative supply route to the road between the Afghan capital and the Pakistani border, which has come under attack from militants on both sides of the frontier this year.

Zamir Kabulov, the Russian Ambassador to Afghanistan, told The Times in an interview that he believed the deal was no longer valid because Russia suspended military cooperation with Nato last week over its support for Georgia.

Asked if the move by Russia invalidated the agreement, he said: “Of course. Why not? If there is a suspension of military cooperation, this is military cooperation.”

Mr Kabulov also suggested that the stand-off over Georgia could lead Russia to review agreements allowing Nato members to use Russian airspace and to maintain bases in the former Soviet Central Asian states of Uzbekistan, Kyrgyzstan and Tajikistan.

“No one with common sense can expect to cooperate with Russia in one part of the world while acting against it in another,” he said.

His remarks are likely to alarm Nato commanders because the Taleban have been targeting the supply routes of the alliance this year, mimicking tactics used against the British in 1841 and the Soviet Union two decades ago. Nato imports about 70 per cent of its food, fuel, water and equipment from Pakistan via the Khyber Pass, and flies in much of the rest through Russian airspace via bases in Central Asia. It has not started using the “northern corridor” because the deal – covering nonmilitary supplies and nonlethal military equipment – has yet to be cleared with the Central Asian states involved.

The need for an alternative route was highlighted by recent attacks on Nato supply convoys, including one that destroyed 36 fuel tankers in a northwestern Pakistani border town in March. Four US helicopter engines worth $13 million (£7 million) went missing on the way from Kabul to Pakistan in April. Last week militants killed ten French soldiers on the same route 30 miles from Kabul.

Western officials fear that such attacks could increase in the power vacuum in Pakistan created by the resignation of Pervez Musharraf as President last week and the collapse of the coalition Government yesterday.

Vladimir Putin, Russia’s President-turned-Prime-Minister, was the first foreign leader to telephone President Bush after the attacks on September 11, 2001, and has supported the War on Terror ever since. The Kremlin has fears about the spread of Islamic extremism into Central Asia and Muslim regions of Russia, especially Chechnya, where it fought two wars with Muslim rebels in the 1990s.

However, many Russian officials have bitter memories of the Soviet defeat in Afghanistan and strong reservations about the US presence in Central Asia, which they see as their strategic backyard.

“It’s not in Russia’s interests for Nato to be defeated and leave behind all these problems,” Mr Kabulov, who worked at the Soviet Embassy in Kabul from 1983 to 1987, said. “We’d prefer Nato to complete its job and then leave this unnatural geography.

“But at the same time, we’ll be the last ones to moan about Nato’s departure.”

A Nato spokesman declined to respond to Mr Kabulov’s comments and said that Russia had not informed the alliance officially of any decision to annul the northern corridor agreement.

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