DALIAN- More than 500 fishing boats in Dalian, a coastal city in northeast China's Liaoning Province, set off Monday to clean up the crude oil that gushed into the sea after an oil pipe exploded at Dalian Xingang Harbor.

At 6:30 am, hundreds of fishing boats gathered at Dagushan Jinshan fishing port in Dalian to load oil absorbing and dispersant materials.

The fishing boats will clean up the oil which lies south of Dalian's Golden Pebble Beach and east of Bangchui Island, a spokesman of Dalian government said.

"The small boats are simple to maneuver so they can quickly clean up the spill," said the spokesman.

A dark brown belt of crude oil and other pollution stretches at least 50 square kilometers out from Dalian's Xingang Harbor.

Strong onshore winds had helped contain the polluted areas to 45 square kilometers Sunday, Luan Yuxuan, deputy director of Dalian City Oceanic and Fishery Administration, said Monday.

The cleanup started Saturday with the use of an initial 20 vessels, including four patrol boats from the provincial maritime bureau.

So far, 24 oil cleaning vessels have been mobilized and more than 800 fishing boats have also joined the cleanup efforts, said Luan.

Luan said the job would be finished in four to five days at best.

A total of 280 tonnes of oil has been collected by the local fishery department, and another 180 tonnes has been collected by the oceanic department, Luo said.

But the total amount of oil spilled into the sea remained unknown, he said.

A large quantity of oil spill dispersant and absorption felt have been shipped in from Tianjin and Shandong Province, maritime officials said.

Fire engulfed the harbor Friday evening, after an oil pipeline exploded and triggered an adjacent pipeline to explode as well. Flames raged for 15 hours before they were extinguished Saturday morning. No one was hurt in the explosions or subsequent fire.

A team was established Sunday morning to investigate the incident.