BEIJING, July 18 (Xinhua) -- The Olympic co-host city Qingdao has applied underwater robots and video cameras to ensure safety of the upcoming Olympic sailing competitions, the event organizers said on Friday.

　　"The naval forces had launched underwater monitoring system, including setting underwater video cameras, robots and divers in the open port, to watch potential threats," said Qingdao vice mayor Zang Aimin, also vice chairperson of the Qingdao Olympic Sailing Committee.

　　The Olympic sailing events run from Aug. 9 to 23 in Qingdao, a coastal city in east China's Shandong Province. Some 400 athletes from 65 countries and regions will compete for 11 gold medals.

　　Zang said that the massive algae bloom threatening the Olympic sailing venue had almost been cleared, with only 0.1 square kilometer left.

　　Two barriers have been installed to keep algae from the sailing venues that cover 50 square kilometers. Ships will also monitor the area, according to Zang.

　　"More than 30 Olympic sailing teams with over 100 boats currently training there haven't been affected by the algae," she added.

　　Starting in mid-June, the sea-blanketing algae bloom floated from the Yellow Sea coated Qiangdao, covering 32 percent of the sailing venue at the peak of the outbreak.

　　More than 1,400 boats and 10,000 troops and volunteers were dispatched at one clean-up stage, and one million tons of algae had been cleared by July 15.

　　Zang said the city had invested a total of 3.28 billion yuan (481 million U.S. dollars ) to build the Olympic Sailing venues, and the final preparation for the Olympics is well underway.

　　With the launching of a "blue sky" campaign involving 26 action plans, Qingdao is expected to witness blue sky and fairly good air quality in the whole month of August.