China's Olympic co-host city Qingdao has appealed for help to contain an algae bloom that has coated its offshore waters.

Qingdao, which will host Olympic sailing events during the Beijing Games in August, had asked coastal cities to help in clean-up efforts, and had already co-opted 10,000 local residents and troops, and hundreds of boats to dredge the resort town's bays.

Authorities have so far cleaned 8,626 tonnes of floating weed from coastal waters and scooped up another 13,665 tonnes that had washed up on local beaches, a report posted on the Qingdao government website said.

A microbiology professor said: "This is more severe than common algae outbreaks," adding that ferries to nearby islands had suspended services for several days.

Pictures carried by local media showed officials and soldiers raking up piles of spongy weed.

A witness reported seeing trucks loaded with weed parked on local beaches.

Media reports, which referred to the green tide as "hu tai" meaning "water-borne lichen", said it had been caused by an untimely confluence of wind and currents influenced by stormy conditions in southern China.

China's coastal waters and inland lakes regularly suffer algae blooms, often exacerbated by pollution from chemical factories and fertiliser run-off from farms.

A major outbreak last year on eastern China's Tai Lake cut off drinking water to millions of residents in Jiangsu province's Wuxi city.

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