Tehran: President Mahmoud Ahmadinejad said on Tuesday he wants Russia to help build two more nuclear power units at the Bushehr complex, Russian news agencies reported.

"Iran is ready to cooperate with Russia in building the second and third units at Bushehr," Ahmadinejad was quoted as saying by Russia's RIA news agency after a meeting with Russian President Vladimir Putin.

Russia is helping to build the initial Bushehr nuclear power plant on the Gulf but has until now repeatedly put back the start-up date citing Iranian payment delays. Tehran denies any payment problems.

The Iranian call for further co-operation follows a joint declaration issued after a meeting between the two leaders which stated the still unfinished first plant would be completed on time by Russian contractors.

"The Bushehr nuclear power plant will be constructed and brought into operation in line with the agreed upon schedule," the statement said.

"The parties ... reaffirmed that it will continue to be pursued strictly in line with their commitments under the treaty on the non-proliferation of nuclear weapons."

Ahmadinejad described the outcome of the visit as a "milestone in relations between the countries", Russian agency TASS reported.

The statement did not give precise guarantees on when Russia might start delivering fuel to Iran's first nuclear power plant.

"At the moment Russia and Iran are discussing the issue of changing the contract. In general there is a common understanding of the problem," Putin told Iranian media in an interview.

"As soon as this is solved, supplies of nuclear fuel will start," he said after meeting Ahmadinejad, who is defying pressure to suspend atomic work the West suspects is aimed at building nuclear bombs.