As many as 30 people are feared dead after a ship capsized and quickly sank in choppy Persian Gulf waters off the Qatari capital Doha, the vessel's operator said Wednesday.

The accident occurred at about 6:30 Tuesday morning as the MV Demas Victory tried to return to port in bad weather, said George Mathew, the general manager of the ship's operator. The ship provides support to offshore oil and gas platforms.

Mathew said the ship's captain had requested permission to enter the channel leading to Doha's harbor but was told to remain at an outer anchorage because of the rough conditions.

"At that time, a huge swell and strong wind hit him and the vessel was capsized," Mathew said in an interview. "It completely sank in three minutes."

Mathew said the ship was carrying 9 crew, along with 24 employees of the charterer HBK Power Cleaning and two caterers working for a company hired by HBK.

Five crew members — three Indians and two Indonesians — were rescued. They were on deck or in the wheelhouse at the time of the accident, Mathew said.

A spokesman for HBK, who spoke on condition of anonymity because of the sensitivity of the situation, said five bodies had been recovered by late Wednesday afternoon. He said three of the dead were Nepalese and two were Indian.

Mathew said he feared those who are still missing were killed because they were unable to escape their sleeping cabins as the ship went down.

The ship, flagged in the Caribbean island nation of St. Vincent & The Grenadines, is operated by Dubai-based Midgulf Offshore Ship Chartering LLC on behalf of owner Demas Marine Inc. It was built in 1979 and has been operated by Midgulf since January 2005.

HBK said its passengers consisted of 12 Nepalese, 11 Indians and one Bangladeshi. The caterers were also Indian, the company said.

HBK Power Cleaning is a division of Doha-based HBK Holding, a conglomerate owned by members of Qatar's ruling family. It specializes in applying corrosion-protection coatings to oil rigs and other structures.

Qatari government officials could not be reached for comment.