The United States pushed for a swift vote to apply UN sanctions on Zimbabwe's leaders yesterday after Russia backed away from an apparent deal at the G8 summit.

The US delegation asked initially for the UN Security Council to take a vote last night, even though Russia and China said they were not ready.

Crisis talks in the UN corridors led to the vote being postponed until today because of the risk of a veto by Moscow or Beijing.

Uncertainty about the timing remained, however, because Russian diplomats told other members of the council that Moscow would not be ready to vote until tomorrow.

The diplomatic drama came after signs that Dmitri Medvedev, the new Russian President, had changed tack on Zimbabwe, despite an apparent agreement by world leaders at the G8 summit in the Japanese resort of Lake Toya. The G8 leaders issued a strong statement on Tuesday threatening further steps against Zimbabwe, including “financial and other measures against those individuals responsible for the violence”.

Gordon Brown flew home from the summit yesterday and talked confidently about the unanimity of G8 leaders about Zimbabwe.

“The mood [in the G8] is outrage against what is happening in Zimbabwe, disgust at the behaviour of the Zimbabwe regime, an acceptance by all of them that this is an illegitimate regime that has got blood on its hands,” the Prime Minister said. “With these new sanctions, there will be no safe haven and no hiding place for the criminal cabal that now makes up the Mugabe regime.”

Mr Brown's hopes for a quick vote on UN sanctions were thrown into question when Mr Medvedev suggested that Russia would not support such measures in the UN Security Council, which is the only body able to impose them. “The elections that took place in Zimbabwe have left the feeling of dissatisfaction in the international community,” he told a press conference in Lake Toya. “The statement contains recommendations of how the world community should be reacting, but there are no statements regarding the decision that would be taken by the United Nations in particular.”

The US proposal would declare an arms embargo on Zimbabwe and impose a travel ban and freeze assets on Robert Mugabe and 13 other officials who were judged responsible for election-related abuses. Among them are the commander of the Army, the police commissioner, the justice and defence ministers and the governor of the central bank in Zimbabwe.

The draft resolution would also require the UN to name a representative to Zimbabwe, effectively sidelining Thabo Mbeki, the President of South Africa, as mediator.

South Africa has led opposition to the US proposal in the Security Council and is expected to vote against it. Libya, Indonesia and Vietnam are expected to follow South Africa's lead.

Western diplomats have said that they will still have the nine votes needed to secure its adoption in the 15-nation council, unless Russia or China veto it. China, which has attracted worldwide protests over its role in Darfur, had shown no appetite for an embarrassing fight over Zimbabwe before the Olympic Games in Beijing next month, diplomats said.

Russia has objected strongly to a provision in the US draft that called for a political solution reflecting the results of the first round of the presidential election on March 29, which was won by the opposition candidate Morgan Tsvangirai.

Vitali Churkin, the Russian UN representative, has balked at the Security Council extending its jurisdiction to effectively certify the results of elections in UN member states.

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