In a statement, the Rosatom agency said the plant's contractor, Atomstroiexport, had "received the first payment for building of the Bushehr nuclear power station since the cut in financing."

"Our Iranian partners have overcome the difficulties they had. This is positive but still far from compensates for the period of non-payment for the needs of the site," the statement said.

Rosatom spokesman Sergei Novikov told AFP that construction of the plant had been thrown off course by the non-payments and it would not be possible to launch the power station in September as planned.

"Construction of the power station can't be completed by the date initially planned," Novikov said.

Russia earlier said it had not received payment for work at the power station in southern Iran since January.

The Bushehr plant is a symbol of the long-standing ties between Tehran and Moscow.

The United States has urged Russia to stop construction work at Bushehr due to suspicions about the Islamic republic's nuclear programme.

Iran says it is purely developing civilian nuclear energy but the West suspects it of trying to develop nuclear weapons.

Novikov did not say how much had been paid but said it would ensure the normal functioning of the site for half a month.

He added that 2,000 Russian workers were continuing work at the site.

The Bushehr project has been plagued by difficulties and subject to repeated delays.

Despite the two countries' relative closeness, Moscow supported a United Nations Security Council resolution on Saturday that slapped new sanctions on Iran in a bid to pressure it into freezing its uranium enrichment programme.

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