Beijing authorities are cranking up an "Olympic greening" campaign by decorating roofs with gardens from next year.

The municipal government will finance the greening of 100,000 square meters of roofs next year, mainly in areas close to the 2008 Olympic facilities, the Capital International Airport and along the second and third arterial ring roads, said Yang Zhihua, an official with Beijing Municipal Gardening and Forestation Bureau.

About eight million square meters of grayish roofs in the airport area made an ugly first impression on first-time travelers to the Chinese capital, he added.

A satellite survey found 69 million square meters of barren roofs within the Fourth Ring Road that encircles the busiest areas of Beijing. Experts say at least 30 million square meters can be covered with greenery.

Yang's bureau has started shortlisting roofs that can support gardens.

"We'll select roofs that are highly waterproof and can support at least 150 kilograms per square meter," he said.

Roofs that fail these standards will be painted more colorfully and flat ones will be sloped to improve water run-off, according to the bureau.

Between 2007 and 2010, the municipal government will allocate 10 million yuan (1.25 million U.S. dollars) annually to finance the greening of at least 100,000 square meters of roofs a year, said Qiang Jian, vice director of the bureau.

He also called on local businesses, particularly real estate developers, to contribute.

Beijing had 38,877 hectares of public green areas at the end of 2005, or 11 square meters per capita, which the city aims to expand to 15 square meters by 2010.