France is reportedly carrying out sea trials of Sebastopol, Russia’s second Mistral-class amphibious helicopter carrier.

The warship is said to be undergoing five-days of testing at the Saint-Nazaire port in western France, without the presence of any Russian Navy personnel aboard, reported AFP.

Sevastopol is one of two vessels built as part of a $1.5bn deal signed by France and Russia in June 2011.

The first carrier, Vladivostok, was supposed to join the Russian Navy by the end of 2014, followed by Sevastopol this year.

Deliveries were suspended after criticism from the UK and US regarding Moscow’s reported involvement in the Ukrainian crisis.

"Deliveries of the vessels were suspended after criticism regarding Moscow’s reported involvement in the Ukrainian crisis."

Meanwhile, Sputnik reported Rosoboronexport director general Anatoly P Isaykin as saying that France will return the amount that Russia paid for the two helicopter carriers.

Reports also emerged that the Vladivostok carrier could be relocated from Saint-Nazaire to Brest due to its high maintenance cost.

Le Telegramme reported that DCNS and STX shipyard operators have to pay maintenance fees of €2.5m ($2.7m).

Capable of cruising at a maximum speed of 19k, the 199m-long, 22,000t Mistral-class ships are equipped with MRR-3D NG surveillance radar and a high-performance communications suite for humanitarian missions and a range of other operations.

They are integrated with two Breda Mauser 30mm naval guns, four 12.7mm machine guns and two MBDA France Simbad launchers for the Mistral air defence missile.