Thousands of soldiers and volunteers in east China's coastal city of Qingdao, host of the Olympic sailing events, are still battling a major algae bloom on Friday.

More than 1,300 vessels were at sea cleaning the foul-smelling algae, and inflatable barriers were placed near the coastline to prevent the algae from encroaching on the shore.

According to an emergency headquarters set up to clean the algae, its coverage in the sailing competition areas, which span more than 50 square kilometers, had shrunk from 32 percent five days ago to less than 10 percent.

But an aerial survey shows 339 square kilometers of the green growth floating along the shoreline of the city and parts of the Yellow Sea, authorities said.

More than 110,000 soldiers and volunteers have been engaged in frantic efforts to cleaning the weeds, which was first spotted at the end of May and started to bloom in mid-June.

On Friday alone, more than 20,000 tons of the algae were cleared from the water.

At the Olympic sailing base, where the boats are docked during the Olympics, sporadic remains of algae floated on the water off the coast in the water. Dozens of boats were spotted at sea gathering the algae.

Along beaches near the base, soldiers were bagging piles of green algae which were dragged out of the water.

By Friday, about 360,000 tons of the algae have been removed from the water and seashore. Officials planned to wipe out the algae, called enteromorpha prolifera, before July 15.

The sailing competitions are scheduled from Aug. 9 to 23.

Local residents said algae blooms were common in previous years, but they had never seen so much of it before.

"Last week, the air was rancid because of the algae, and we all shut our windows," said Zhang Xiaolei, whose office is near the coast at the May 4th Square.

"It's far better now than a few days before, and the water is clearer," she said.

Authorities have advised against swimming and fishing along the coast.

The algae also covered parts of a training area, where sailors from more than 30 countries are training, and sometimes blocked sailing routes and affected preparations for the Games.

Sailors said they had to stop during training to clean the algae off their boats. "I've seen algae blooms when we competed in Britain, Germany and other parts of the world, but not this big," said Karnoutsos Akis, a Greek coach.

By Friday, marine workers had driven 280 cement columns into the water to stabilize oil buffers keep the algae out to sea. The Shandong Maritime Administration said 7,200 meters of oil buffers had been put in place, and an additional 24,800 meters were needed.

Experts from the State Oceanic Administration (SOA) are working to determine the source and cause of the algae outbreak.

The SOA was monitoring the route of the algae flow into the Olympic venue with current bottles. Experts dropped 80 bottles in the water around the venue after the bloom was spotted.

They concluded some algae was from the waters of Rizhao and Jiaonan to the south of Qingdao.

(Xinhua News Agency July 5, 2008)