Russia's top naval commander Saturday insisted the purchase of French warships would only go ahead if it included a transfer of technology, warning otherwise there was "no point" to the deal.
The comments by Admiral Vladimir Vysotsky came a day after French President Nicolas Sarkozy assured workers at a French shipyard that the decision to seal the deal with Russia was "certain".
"What is important here is to obtain the possibility of a transfer of key, fundamental technologies... not just in ship building but in several other areas," Vysotsky told the Echo of Moscow radio.
"This is without doubt the main condition for this transaction. If this does not happen then there is no point in undertaking this," he added.
"We do not need the ship but we do need its possibilities.
"We need its equipment. The point of the ship is in its absolute multi-functionality," he said.
Russia has been negotiating with France for months to buy the Mistral-class helicopter carriers but the deal has yet to be finalised, with the issue of technology transfer apparently the main sticking point.
Russian Prime Minister Vladimir Putin told AFP last month that Moscow would only go ahead with the deal if it included a transfer of the technology that makes the Mistral one of the most powerful in the French fleet.
However Vysotsky's statement is the bluntest yet from a Russian military official about where Moscow sees its interests in the deal.
The deal would be the first sale of advanced military hardware to Russia by a NATO country and the sale has worried ex-Soviet states who now have tense ties with Russia, as well as some lawmakers in the United States.
Vysotsky said that other countries possessed technologies which Russia does not have and officials were "being crafty" if they claimed that Russia could develop these on its own.
Purchase of the ships and their equipment is seen as a major pillar in Russia's strategy to transform its armed forces from a structure inherited from the Soviet Union into a modern and dynamic fighting force.
The ships cost around 500 million euros (600 million dollars) each and Russia would purchase up to four of the vessels and also obtain the right to manufacture more at its own shipyards.
Vysotsky confirmed that the deal was now being overseen by one of Russia's most powerful figures and close Putin ally, Deputy Prime Minister Igor Sechin, who media expect to drive a hard bargain on the issue.