AT least ten crew members are reported to have been killed and nine others are understood to be missing after two Tanzanian-flagged LPG carriers caught fire in the Kerch Strait near Crimea.

An explosion aboard the 4,086gt LPG carrier Maestro started a fire at around 18:00 local time on January 21, according to reports received by Lloyd’s List Intelligence’s casualty service.

Russia's state news agency TASS, reported that a second vessel, believed to be the Tanzanian-flagged 4,444gt LPG carrier Venice, but widely reported as being named Candy, was also involved in the blaze.

Nine people are missing after the fire broke out onboard two vessels near the Kerch Strait, the press service of the Federal Agency for Maritime and River Transport told TASS.

"Twelve people were rescued, nine people are missing,'' the press service said. ``Thirty-two people in total. It turned out that there was also an intern from Tripoli onboard the Maestro ship."

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There is a threat of an explosion onboard the two vessels, and the rescue operation continues, a spokesman for the Novorossiisk maritime rescue center told TASS.

"The rescue operation will continue until all of the crew members are found,'' he said. ``There is a threat of gas explosion."

The cause of the explosion is not yet known, however unconfirmed reports from the Russian news agency RIA said the two vessels were engaged in a ship-to-ship transfer.

Initial reports suggested that a fire and an explosion on one ship had spread to the second.

The Venice had loaded a cargo of LPG from the Russian port of Temryukskiy on January 20 before sailing with a reported destination of Lebanon.

The Maestro had been sailing from Istanbul with a destination recorded as Temryuk in Russia.

The Maestro is one of several vessels listed as still subject to US sanctions for delivering restricted cargo to Syria.

A rescue operation is underway and authorities in the Crimean city of Kerch are now preparing to receive the victims.

Restrictions on traffic near the Kerch strait are in place following the incident.

The crew members were sailing in "neutral waters" in the Black Sea when the incident occurred, authorities told the BBC.

The Kerch Strait is a focus of tension between Russia and Ukraine.

In November, Russian border guards seized three Ukrainian naval vessels near the narrow channel, which links the Black Sea with the Sea of Azov.

In response, Ukraine imposed martial law for 30 days in several regions around the country and barred entry to male Russian nationals aged 16 to 60 for the duration of the state of emergency.

On January 16, a Moscow court extended the custody of all the detained Ukrainian sailors for three months, Russian state news agency TASS reported.