Dmitri Medvedev, the new Russian President, met Gordon Brown for the first time today as the two leaders attempted to thaw relations after a period of diplomatic hostility.

Relations between Britain and Russia has been strained over the past two years. At last year's G8 summit Tony Blair is believed to have become embroiled in angry exchanges with Vladimir Putin, Mr Medvedev's predecessor.

Mr Medvedev attended this year's conference, at Lake Toya on the Japanese island of Hokkaido, without Mr Putin, but there are suspicions that the former President is pulling strings behind the scenes.

Speaking at the start of the 45-minute meeting this morning — one of four meetings with Western leaders — Mr Medvedev said that the relationship between Russia and Britain had "enormous potential".

"This reveals the enormous potential our relationship enjoys, even with certain problems faced there, and this is a good chance to discuss the potential of development with respect to the economy and trade and humanitarian issues," the Russian leader said, speaking through interpreters.

During the meeting, Mr Brown is believed to have raised Russia's refusal to extradite the former KGB officer Andrei Lugovoy, the chief suspect in the London poisoning of the dissident Alexander Litvinenko. It was this incident that caused the rift between Russia and Britain that culminated in last year's tit-for-tat expulsions of diplomats.

Further tension has been stoked by the treatment of the British Council in Russia, with numerous employees arrested and the council's operations hampered, as well as a dispute with the oil giant BP over its operations in Russia.

"International relations always require people to come towards each other. The Prime Minister hopes his bilateral meeting with Mr Medvedev will be a constructive discussion on a wide range of issues," a British official said.

In what represented the biggest round of diplomacy since he took power, Mr Medvedev held separate talks with President Bush, Angela Merkel, the German Chancellor, and Nicolas Sarkozy, the French President.

After the meeting with Mr Bush, a senior aide to Mr Medvedev said that the talks had been "constructive". However, he added that the United States had failed to ease Russia’s concerns about its plans for a Europe-based missile shield.

"There is no real progress," Sergei Prikhodko, said. He added that Mr Medvedev warned Mr Bush that deploying interceptor missiles for the system in the former Soviet republic of Lithuania "would be absolutely unacceptable for the Russian Federation".

Mr Prikhodko said that the talks were "exclusively well-intentioned, constructive and open, but at times critical." He said that Mr Medvedev believes "the overall balance of Russian-American relations is without a doubt positive".

Elsewhere at the G8 summit this morning, leaders were locked in tense negotiations over the future of aid to Africa, as Britain and Japan resisted efforts by France and Italy to water down historic promises made at the 2005 Gleneagles summit to double development in the world’s poorest continent.

The pressure to water down the proposals comes from Nicolas Sarkozy, the French President, and Italian leader Silvio Berlusconi, who both face pressure to trim their domestic spending. It is opposed by Mr Brown and by the Japanese Prime Minister, Yasuo Fukuda.

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