The Mistral can carry troops, helicopters and armoured vehicles

France has agreed to sell Russia an advanced warship and is considering a request from Moscow for three others, French defence officials say.

It would be the first arms deal of its kind between Russia and a Nato member.

It remains unclear when or where the 23,000-tonne Mistral class warship will be built.

The deal, which would increase Russia's capacity to launch amphibious offensives, will alarm ex-Soviet states such as Georgia, analysts say.

Russia and Georgia fought a short war in August 2008.

French President Nicolas Sarkozy had approved the sale of one Mistral, but Moscow naval officials had then asked for a further three ships, said Jacques de Lajugie of the French arms agency DGA.

The deal has not yet been signed.

With an estimated cost of up to 500 million euros, the Mistral is an assault ship that can carry troops, helicopters and armoured vehicles.

Russia has reportedly been keen to buy the 980ft (299m) ship from France to modernise an ageing armoury.

The prospect that the ship could be used against Nato members or their allies has raised concerns in some parts of the alliance. A US official travelling with defence secretary Robert Gates to Paris on Monday said "we have questions" for France about the order.