A massive algae "green tide" is likely to persist in east China's beachside resort of Qingdao for the next few days, although thousands of tonnes of the seaweed clogging up the coastline has been cleared, according to marine officials.

Huang Juan, deputy head of the North China Sea Marine Forecasting of State Oceanic Administration, told Xinhua on Saturday that 1,558 square km of the algae bloom spreading over 8,620 square km on the Yellow Sea has been washed to waters near Qingdao. Among the coverage, 49 square km of the algae are still choking the city's seashore.

"The algae bloom is likely to persist in the area for the next three days as winds are still pushing the green tide ashore," Huang said.

Wang Shulian, deputy head of the Qingdao Marine and Fishery Bureau said, local authorities have made a combat by mobilizing some 3,000 people to salvage 62,533 tonnes of the algae since it first appeared in June.

"We have made early preventions by building 20,000 meters long iron fences on the sea to protect the beachside resorts and the city's Olympic Sailing Center," Wang said.

The fences with mechanical devices have proved effective in facilitating the seaweed collection.

She said the algae bloom this year was more serious than before and came earlier. But it has not done harm to the local tourism and aquaculture thanks to the combatting efforts.

Local residents panicked when they first saw the seaweed bloom in 2008, when it posed a threat to the Olympic sailing events scheduled in Qingdao.

Through the years as the green tide becomes frequent in summer, the public have been aware that the algae is not toxic. Holiday makers have kept flocking to Qingdao for summer vacation despite media reports on the green tide.

Liu Tao, an associate professor with the Ocean University of China, said the algae absorb nitrogen and phosphorus pollutants in the seawater. But if it is not timely disposed, mats of the seaweed garbage on shore would incur new pollution.

The marine official Wang Shulian said the authorities have seen to all of the collected algae sent to the treatment facility of a bio-engineering development company under the Ocean University of China.

"More than 80 percent of the algae are recycled for making fertilizer, animal feed and food additives," she said adding the algae fertilizer has become a hot-selling product for organic farming.

She said the university has been working on a program to develop green algae feed for aquatic animals.