TEHRAN, Feb 26: Russia and Iran on Saturday again delayed the signing of a controversial contract to supply the Islamic republic with fuel for its first nuclear power station, amid a new dispute over the plant's opening date.

Iranian officials said more talks were needed after they rejected a proposal from Moscow to delay the opening of the plant in the Gulf port of Bushehr until June next year.

"The Russians are proposing bringing the Bushehr power station on line in June 2006. We rejected this proposal," Iranian Atomic Energy Organization vice-president Mohammad Saidi told state television.

"Discussions will need to continue in Bushehr tomorrow for us to reach agreement."

Russia's top atomic energy official Alexander Rumyantsev and his Iranian counterpart Gholamreza Aghazadeh had been poised to sign the agreement earlier on Saturday, but reporters were told that instead negotiations were still "dragging on".

"We do not know when they will conclude," said a spokesman for the Atomic Energy Organisation, Yaghoub Jabarian. He added that a rescheduled press conference would "maybe" take place on Sunday.

It was the latest and most spectacular hitch to a contract that the United States has been trying to convince Russia not to sign.

In a concession to the United States, Moscow had refused to provide fuel for the Bushehr plant in southern Iran unless spent fuel, which potentially could be reprocessed and upgraded to weapons use, was returned.

Iran agreed to this condition after close to two years of talks that had already pushed the plant's opening back to next January.

Saidi said he was still hopeful the deal could be signed during Rumyantsev's visit to Bushehr on Sunday.

The deal would cap an $800 million (606-million-euro) contract to build and bring on line the Bushehr reactor.

Bushehr was raised during a summit between US President George W. Bush and Russian President Vladimir Putin in Bratislava on Thursday,.-AFP