July 2 (Bloomberg) -- Olympic organizers struggling to stem an algae bloom at the sailing venue in Qingdao are turning to another threat: a plague of locusts heading for Beijing.

The northern Chinese province of Inner Mongolia has mobilized 33,000 people to repel swarms of locusts that may reach the capital during next month's Olympics, the official Xinhua News Agency said. The locusts have come within 430 kilometers (267 miles) of Beijing and have infested an area of 1.3 million hectares (5,000 square miles), Xinhua said.

``We are aware and we're coordinating with the relevant authorities to look into the issue,'' said Sun Weide, a Beijing Games organizing committee spokesman, in an interview today.

The locust alert comes as 10,000 workers scoop up blue- green algae along the coast that will stage Olympic sailing and as Beijing grapples to cut pollution for the Aug. 8-24 games.

Officials aim to complete the Qingdao clean-up by July 15. Locusts in full flight may not be so easy to tackle. Inner Mongolia authorities are using 200 tons of pesticides, 100,000 sprayers and four airplanes to kill the pests, Xinhua reported.

The flying insects have infested land in Xilinguole Meng county, including Chifeng city, Gao Wenyuan, who heads Inner Mongolia's grassland office, was cited as saying. Chifeng is 430 kilometers to the northeast of Beijing.

And the worst may yet follow.

Cooler-than-average temperatures in spring delayed the hatching of many locusts until late July and August, the grassland monitoring and supervision center at China's agricultural ministry said in a statement.

`More Apparent'

``The larvae are in the hatching stage in the counties and cities near Beijing,'' Gao was quoted as saying. ``The plague is becoming more apparent.''

The algae bloom was prompted by warmer weather and higher rainfall in the southeast of China, while the locust plague has arisen because of warmer and drier conditions to the north of Beijing, according to the supervision center.

About 4,000 troops are helping the Qingdao clean-up, which has removed 150,000 tons of algae since June 25, Qingdao's government said on its Web site. Beijing officials yesterday traveled to Qingdao, about 500 miles to the southeast of Beijing, to discuss the issue with local organizers.

Beijing is closing factories and taking half the cars off its roads from this month in a bid to reduce smog. The International Olympic Committee said some athletes may be at risk from pollution.

To contact the reporters on this story: Wing-Gar Cheng in Beijing at wgcheng@bloomberg.net.

Last Updated: July 2, 2008 03:35 EDT