Beijing on Wednesday started cleaning the lower reaches of a river that flows through the northern part of the city in a bid to improve the environment around the Olympic Park being built for the 2008 Olympics.

The project, which will cost 640 million yuan (US$80 million), will clear away silt, improve the water quality, and build concrete banks along the Qinghe River, a spokesman with the Beijing Municipal Water Authority said.

The current work is the second phase of the clean up and should be finished by the end of next year, he said.

Last year, local government cleaned up the upper reaches of the Qinghe River, which originates in the Biyun Temple in the western suburbs of Beijing, he said.

The Olympic Park will cover 1,085 hectares, including a 680-hectare forest and a 405-hectare national sport center which will host field hockey, archery and tennis competitions during 2008 Olympic Games.