Iran and Russia have agreed to speed up construction of a controversial nuclear power plant in southern Iran.

The deal brings forward completion by three months, with control of the plant, at Bushehr, being handed over to the Iranians next year.

The BBC Iranian affairs analyst says Teheran had feared the Russians were delaying the project under pressure from the United States, which has expressed concern that it could be used to develop nuclear weapons -- something denied by Russia and Iran.

The deal was signed at the end of a four-day visit to Iran by the Russian nuclear power minister, Yevgeny Adamov, and resolves differences over payment of eight-hundred million dollars for the contract -- a major concern to Moscow.

The two sides also agreed to examine the feasibility of a second reactor and other projects.