Efforts were under way yesterday to contain and clean up a large oil slick after pipeline explosions at a northeastern Chinese port.

Workers take samples of water off the coast at northeastern Dalian City yesterday as firefighters continue to cool down oil tanks after they had extinguished fires caused by two pipeline explosions on Friday night. Efforts are under way to contain and clean up a large oil slick resulting from the blasts. [Shanghai Daily]

Maritime workers on 20 boats were sent to install fencing to stop the spilled oil from spreading further in Dalian's Xingang Harbor.

The slick had contaminated an area estimated to be about 50 square kilometers off the coast of Liaoning Province.

A team has been established to investigate the explosions, local authorities said yesterday.

The investigation began yesterday morning but the cause of the accident had yet to be determined, said Sun Benqiang, deputy chief of the work safety bureau of Dalian City.

A 0.9-meter-diameter oil pipeline exploded at 6pm on Friday near Xingang Harbor, triggering another explosion at an adjacent smaller pipeline.

Both pipelines, owned by China National Petroleum Corp, caught fire.

The blaze at the larger pipeline was extinguished around midnight but at least five subsequent explosions fueled the flames at the smaller pipeline. The fire was mostly extinguished by Saturday morning, some 15 hours after the initial explosion.

The accident happened after a 300,000 ton oil tanker discharged its load at the harbor. The tanker left the harbor safely.

"Whether CNPC or the tanker should be blamed for the accident is yet to be determined," said Sun.

The explosions and fires caused no casualties, a city government spokesman said. The scene of the accident was far from residential areas.

The spill had "seriously polluted" 11 square kilometers of sea and "slightly affected" 50 square kilometers of sea, said Wu Guogong, deputy chief of Dalian's environmental protection bureau.

CNPC said yesterday it would do its best to reduce the impact of the pipeline explosions. Oil had stopped leaking into the sea as a valve has been closed. The oil that entered the sea has been fenced off and contained, the company said.

Monitoring of the air and sea environment has been stepped up in the affected areas, according to the company.

Smoke from the explosions and fires at the scene has begun to clear but still irritates people's eyes and throats.

The pipelines linked on-land oil tanks and tankers.

Yesterday, an official from the Dalian environmental protection bureau said the oil contamination was being cleared up and had no direct impact on the city itself. However, he said it was unclear how much oil had leaked from the pipelines.

President Hu Jintao and Premier Wen Jiabao urged all-out efforts to battle the blaze and stop the oil spill.

Vice Premier Zhang Dejiang rushed to the scene on Friday night to direct operations.