Wednesday's talks "ended with practically no result," an Atomstroiexport source told the ITAR-TASS news agency.

But an Atomstroiexport spokesman told AFP the talks, which are over money that Russia says Iran has delayed paying, would nevertheless continue Thursday.

"Negotiations went on for six hours. The two sides discussed the necessity of immediate payment and the issue of delivering material by third parties," he added.

Iran's delegation in its turn denied any delay in payment, saying that Tehran was in advance of its payment schedule.

"There are no financial problems between Iran and Russia," said Iran's Foreign Minister Manushehr Mottaki.

Russia's nuclear energy agency Rosatom said last month that Moscow could delay the delivery of nuclear fuel for the reactor at Bushehr due to problems with Iran's payments.

Russia's announcement came as pressure continues on Iran to suspend its controversial nuclear program and uranium enrichment programs in particular.

The central reactor at Bushehr was due to be launched in September, and the fuel is due to be delivered six months ahead of the launch, in March.

The United States, which accuse Iran of intending to use nuclear energy for military ends, has called on Russia to suspend construction at Bushehr.

Tehran assured that its nuclear program would be used for civilian purposes only.

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