A helicopter has joined the search for seven Chinese fishermen missing for two days in the fog-shrouded East China Sea, although rescuers hold out little hope of their survival.

The helicopter joined the search after the heavy fog cleared on Friday afternoon.

"The seas are generally calm, but the water temperature is low, below 10 degrees Celsius," said a spokesman with the Zhejiang Maritime Search and Rescue Center.

"Generally speaking, the chances of their survival are slim if they have fallen into water," he said.

No trace of the fishermen or their vessel, the "Zhepuyu 71090" had been found so far.

"The vessel transmitted no distress signals at the time of its disappearance, possibly on Wednesday night, so it's last known location is unclear," he said.

About 10 rescue boats had been dispatched to the search area near the Langgangshan archipelago, he said.

The crew of the "Zhepuyu 71090", registered in Zhejiang Province, told two other vessels that they would return to Zhoushan Port on Thursday morning after leaving port early on Wednesday.

Local maritime authorities were informed of their disappearance on Thursday morning.

(Xinhua News Agency December 15, 2007)