QINGDAO, Shandong -- All green algae at the Qingdao Olympic sailing venue has been cleared, said an official of the Beijing Organizing Committee for the Games of the XXIX Olympiad (BOCOG) on Tuesday.

Sailors train on the sea in Qingdao, Shandong Province, July 10, 2008.[China Daily]

"The sailing event, which will be held in more than 20 days, will not be threatened by the algae," Wang Wei, vice president of the sailing committee (Qingdao) of BOCOG, told Xinhua.

By Tuesday, more than 1 million tonnes of algae had been cleared.

Starting in mid-June, the coast of Qiangdao was coated with a vast algae bloom that had floated from the Yellow Sea. A bright green covering of algae smothered beaches and extended out several hundred meters. It once covered 32 percent of the sailing venue at the peak of the outbreak.

Hein Verbruggen, International Olympics Committee coordination commission chairman, called the algae outbreak "an unavoidable natural disaster."

After one month's intensified efforts, the local authorities installed two barriers to keep algae out of the Olympic sailing venue that covers 50square kilometers.

The second barrier, 22,000 meters long, was completed on Saturday. It can block algae at wind speeds up to 61 km per hour, local authorities said.

The first 20,000-meter barrier, completed on Friday, stands 100 meters away from the second.

"We will also assign ships to the scene, monitoring the algae," said Jiang Daming, governor of Shandong Province.

"Once algae is found near the barriers, it will be immediately cleared," he added.

Now only sporadic algae could be monitored in that area.

Soldiers and volunteers have been working to remove the unsightly but non-toxic algae. The accumulated algae has been covered by soil and lime to avoid odors. Some might be processed into fertilizer, experts said.

On Tuesday, 303 athletes from 33 countries practised sailing at the venue, though heavy fog shortened the visibility to only 200 meters in the day, Wang Wei said.

The sailing event will take place here from August 8 to 23. More than 400 athletes from nearly 60 countries and regions will compete for 11 gold medals.