Over 23 tonnes of oil-eating bacteria are being used to clean up the oil spill off the coast of northeast China's Dalian City, four days after pipelines exploded near one of China's largest oil reserve bases.

"We received orders Saturday morning from the Maritime Safety Administration for bio-oil-absorbing products," said Yang Jiesen, manager of the research and development center at Beijing Weiyeyuan Bio-Technology Company.

The use of the oil-eating bacteria at the Dalian spill is the first time China has made major use of bio-technology to solve an environment pollution problem.

Although oil fences are being used to prevent the spill from spreading, workers are concerned the situation may worsen if winds blow or rain falls.

"If the crude-oil slick is too thick, the chemical oil-dispersant may not work," a worker spraying the chemical dispersant at the harbor told a Xinhua reporter.

Wu Jin, a PhD at the Institute of Microbiology at the Chinese Academy of Sciences, said oil-eating bacteria, unlike chemical oil-dispersants, can work 24 hours per day and are more environmental friendly.

The Dalian oil spill cleanup started Saturday. By Monday morning, 24 oil clean-up vessels and 800 fishing boats had collected about 460 tonnes of oil.

Wu said the best way to clean up the oil spill in the shortest time possible is to combine physical, chemical and biological cleanup methods.

He also suggested oil-water separation pumps be used to increase the cleanup efficiency.