France has suspended most of its military cooperation with Russia, the French defence minister said Friday, as Paris was still mulling whether to nix the sale of two Mistral warships to Moscow.

Paris has suspended "the majority of its military cooperation with Russia" in the wake of Moscow's takeover of Crimea, Defence Minister Jean-Yves Le Drian said in the Estonian capital Tallinn.

Contacts between the chiefs of staff of France and Russia have been cut and a joint military exercise between the Britain, France and Russia that had been planned for April has also been cancelled, Le Drian said.

France will offer to send four fighter jets to the Baltic states to boost NATO air patrols over the region should the military alliance request them, he added.

But so far Paris has resisted pressure to suspend the controversial Mistral deal with Moscow.

Estonian Defence Minister Urmas Reinsalu criticised the possible sale, after Friday talks with his French counterpart.

Several dozen protesters rallied against the deal in front of the French embassy in the Lithuanian capital Vilnius as Le Drain arrived for talks.

A final decision on the sale is expected in October, according to Le Drian, who also visits fellow NATO member Poland on Friday as part of a Western push to offer security assurances to Eastern allies.

The events in Crimea have rattled nerves in Poland and the three Baltic states, which were under Moscow's thumb before the collapse of the Soviet Union in 1991.

NATO has assured air patrols over the Baltics since they joined the alliance in 2004.

Besides the Rafale and Mirage 2000 aircraft, Paris will also offer to ensure "AWACS patrols from France around twice a week", if asked by NATO, a source close to Le Drian said Friday.

The AWACS aircraft -- Airborne Warning and Control System -- are among the most sophisticated planes in the NATO armoury, capable of monitoring huge swathes of airspace.

French President Francois Hollande said Friday in Brussels the warplanes offer was a demonstration of solidarity with Baltic NATO allies, which "certainly" did not signal military escalation "from our side".

The United States is responsible for the patrols until May. Given the tense situation in Ukraine, it sent additional F-15 fighter jets to the region earlier this month, bringing their total to 10 aircraft.

Poland will then take over the patrols from the US. The ministry source said France will offer the fighter jets, along with the AWACS early warning aircraft, if NATO and Poland deem them necessary.

NATO has already deployed AWACS reconnaissance aircraft to overfly Poland and Romania as part of its efforts to monitor the Ukraine crisis.

Lithuania said Friday that Denmark had also offered additional warplanes to boost NATO's policing mission.