Eighteen Ukrainian sailors were feared dead yesterday after they were trapped underwater in their capsized tugboat in Hong Kong for nearly two full days amid strong currents, rescue officials said.

The sailors would have survived 12 hours after the accident late on Saturday based on the current water temperature of 17 C at the 37-m depth of the wreck, Roger Tupper, director of Hong Kong's marine department, told reporters yesterday.

He said rescue divers continuously knocked on the hull of the ship but the sailors did not signal back.

"Their chances of survival are very slim," said spokeswoman Zhang Jianwen of Guangzhou Salvage Bureau, which is assisting Hong Kong rescue officials.

Tupper said, however, that rescuers will continue their efforts until the Ukrainian vessel is retrieved and the bodies are located. He said poor weather conditions and the upside down position of the wreck hindered rescue efforts.

"The current is very strong. The visibility is very, very low. It's completely dark. Even in daylight, it's absolutely black down 37 m," Tupper said.

Zhang said the Guangzhou Salvage Bureau's divers were tying up the Ukrainian tugboat and preparing to move it to shallower waters to ease rescue efforts.

The trapped sailors are between the ages of 21 and 54, according to information released by Hong Kong's marine department. Their identifies were not immediately available.

The tugboat Neftegaz 67 - which had been detained in Hong Kong for safety problems in 2003 with safety problems - sank late on Saturday when it collided with Chinese cargo ship Yao Hai in waters northwest of Hong Kong's outlying Lantau island.

Editor: Yan