In Shanghai, China's financial hub, floodlights to illuminate some 160buildings, including the world's third tallest TV tower "Oriental Pearl" and the 492-meter-tall World Financial Center, also went down.

Skyscrapers with glowing windows dominating the night skyline are usually considered symbols of affluence and modernization in China. But Saturday night, going dark became trendy.

"I come here just to watch the Oriental Pearl to switch off lights. It's very special tonight because it sends an environmental message to us," citizen Yang Zheying said while standing under the tower.

In many Shanghai outlets of international fastfood chain KFC, people enjoyed candle-lit dinners after the restaurants dimmed lights.

KFC said in a statement earlier that more than 1,300 outlets in 29 Chinese cities would participate the Earth Hour activities.

Initiated in Australia in 2007, Earth Hour is a time zone-by-time zone plan in which people around the world are encouraged to switch off their lights for 60 minutes on the last Saturday night of March to show their concern about global warming and climate change.

About 3,000 cities in more than 80 countries and regions will join this year's campaign, compared with 35 countries last year, according to the organization.

WWF official Wang Limin said in Shanghai that the campaign aimed to send out more and clearer messages to world leaders before they meet in Copenhagen in December to craft a new global pact on curbing emissions of greenhouse gases.

Fast industrialization and urbanization has made China a major emitter and the government has promised to cut the nation's energy consumption by 20 percent by the year of 2010.

In a videotaped speech last week, the United Nations Secretary General Ban Ki-moon called for a global support of Earth Hour, saying it would be a clear message for action on climate change.