The start-up of the first reactor at Iran's Bushehr nuclear plant will be "irreversible" by February next year, a senior Russian nuclear official was quoted by ITAR-TASS news agency as saying Monday.

"Between December 2008 and February 2009 various technical measures will be carried out... that will make the physical start-up process of the first Bushehr reactor irreversible," the report quoted the head of the Russian company working on the facility, Atomstroiexport, as saying.

Atomstroiexport president Leonid Reznikov said he had travelled to Iran earlier this month to check on progress in construction of the plant, ITAR-TASS said.

He said further high-level meetings between Russian and Iranian officials would be held September 29.

The West suspects that Iran is developing nuclear weapons under cover of a civilian nuclear energy program that includes the Bushehr plant. It has imposed sanctions on Teheran and refused to rule out the use of force.

Tehran vehemently denies that it is developing nuclear weapons and says that it has a sovereign right like any country to develop nuclear power.

Last Friday, Iran dismissed as baseless remarks by French President Nicolas Sarkozy that Tehran was pursuing its controversial nuclear programme for military purposes.

Sarkozy's comments, made the previous day during a visit to Iran's regional staunch ally Syria, are "baseless," foreign ministry spokesman Hassan Ghashghavi said in a statement received by AFP.

"Nuclear weapons are not part of Iran's defence doctrine," he added.

Russia signed the deal to build the Bushehr plan in 1995. That deal also included training of Iranian nuclear specialists and delivery of the nuclear fuel needed for the plant's reactor.

Moscow however insists that it is as worried as any Western country about the possibility of Iran acquiring nuclear weapons and has joined Western calls for Tehran to suspend its nuclear enrichment program until international experts verify it is not being used for weapons-making.

Russia and Iran two years ago signed a deal under which the spent nuclear fuel rods from Bushehr must be repatriated to Russia for treatment.

Separately, a US official said the United States would announce later Monday that it was withdrawing a US-Russia civilian nuclear cooperation pact from consideration by Congress over Russia's recent moves in Georgia.