Twenty-five Indians on board the Panamanian cargo vessel MV Rezzak are feared dead, a top official in the Directorate General of Shipping said in Mumbai on Sunday, six days after the ship went missing in the Black Sea.

The ship, which lost contact on February 18, is believed to have sunk off the coast of Turkey, but a search operation was still on.

A life raft had been seen floating in the sea but there were no survivors inside it or near its vicinity. "We are calling up the Turkish authorities. They are searching for survivors, but have not found anyone so far," the official said.

"In the inclement cold weather in the Black Sea, a person can be alive only for 30 minutes even after wearing a life jacket," said the official, adding that bad weather there has further added to the woes.

"We are in a hopeless situation. In all probability they are dead," the official said.

India plans to send an observer wherever the investigation into the episode takes place, the official said.

The vessel, managed by Turkish people and manned by Mumbai-based Pelican marine, was carrying steel billets in bundles from Russia [Images] to Turkey.

There have been reports about bad working condition inside the 25-year-old ship. However, the DG Shipping official said, "these reports are all speculation".

However, the official agreed that the 25-year-old ship did not have the 'best of condition to work'.