The sale by France of a Mistral helicopter-carrying warship to Russia appeared to have soured Monday's meeting between US Defence Secretary Robert Gates and his French counterpart Herve Morin.

Asked about the deal, Gates said he and Morin had 'a good and thorough exchange of views on the subject', suggesting that he had expressed Washington's displeasure.

The French government's defence and weapons agency DGA said Monday that authorities had given the green light for the sale of one Mistral to Moscow.

The Russian government has expressed interest in buying four Mistrals. The request is to be examined in the coming weeks.

Other Western states have been cautious about selling armaments to Russia. The US in particular is concerned about a technology transfer, which could damage NATO interests.

Morin defended the sale, saying Paris believed that it was not possible to act as if Russia had not changed since 1989, and that it was vital for peace and security in Europe to develop a new relationship with Moscow.

'We want to develop a relationship of trust with Russia,' he said.

France invested the record sum of 19.3 billion euros ($26.4 billion) on equipping its army last year, the DGA said Monday.

Despite the worst recession in decades, 60 Rafale fighter jets and 65 war ships and boats were ordered in 2009, the agency said.