The government on Tuesday expressed "strong concern" about the planned sale of French helicopter carriers to Russia, joining some EU countries in opposing the deal as the West believes Russia has failed to meet international demands to end violence in Ukraine.

President Francois Hollande has defied allies Britain and the United States by confirming plans to deliver a helicopter carrier to Russia.

A €1.2 billion ($1.62 billion) contract for two warships, signed by France's then-President Nicolas Sarkozy's conservative government in 2011, was the first by a NATO member country to supply Russia with military equipment.