KYIV — An Estonian cargo ship has sunk off the Ukrainian Black Sea port of Odesa after an explosion, the ship's owners say.

All six crew members of the Helt were able to abandon ship and Ukrainian officials said they were later rescued.

The vessel had been anchored off the coast after leaving port several days ago.

Ukrainian media say the Russian navy had been using the Helt as a shield to hide from Ukrainian weaponry as Russian forces advance towards Odesa.

The Panama-flagged ship is owned by Estonia-based company Vista Shipping Agency. Baltic state Estonia is a member of Nato and has a border with Russia.

Ukraine's military says that Russia is sending amphibious landing vessels to capture Odesa, a city of a million people and a major seaport, as it continues its advance across southern Ukraine.

Russia describes the invasion as a "special military operation" to demilitarise the country.

A Ukrainian official told Lloyd's List the ship was evacuated after sustaining damage below the waterline and listing by 70 degrees.

Captain Igor Ilves, managing director of Vista Shipping Agency, told the BBC there was an explosion on or near the ship but that it was not thought to be a mine.

Capt Ilves, who was not on the ship at the time, said it was not carrying any cargo.

He expressed concern for the fate of the crew, some of whom were initially reported missing.

They comprised four Ukrainians, one Russian and one Belarusian, Capt Ilves added.

Ukraine's infrastructure ministry later reported on its Telegram channel that they had been rescued.

Viktor Vyshniov, deputy head of Ukraine's Maritime Administration, told Reuters they were taken to hospital in the nearby town of Chornomorsk.

Hours earlier, a Bangladeshi-owned ship was hit by an explosion in Ukraine's Black Sea port of Olvia, killing one crew member.

Efforts were being made to rescue the remaining 28 crew of the Banglar Samriddhi, the ship's owner told Reuters.

The Nato Shipping Centre has warned commercial vessels in the northern part of the Black Sea to "exercise caution and stay away from areas where military operations are taking place". — BBC