This year's campaign to promote energy-saving and sustainable development included 48 provinces and cities nationwide.

In Ha Noi, the centre of Viet Nam's 2011 Earth Hour campaign, lights were turned out at major sites such as the Ha Noi Opera House and areas surrounding Hoan Kiem Lake.

At a ceremony to kick off the campaign, Deputy Minister of Industry and Trade Hoang Quoc Vuong called on every individual to protect the global environment and use energy in an efficient and sustainable manner.

Nguyen Van Suu, deputy chairman of the Ha Noi People's Committee, confirmed the capital's authorities and people would take practical action to save power during the year, including turning off unnecessary lights, encouraging green means of transport, increasing tree-growing coverage and effectively using water resources.

The Northern Electricity Corporation, an EVN affiliate, pledged to provide energy-efficient lighting equipment to 250 classrooms in the northern mountainous provinces of Son La, Dien Bien, Lai Chau, Ha Giang and Lao Cai.

In response to the campaign, Hoi An City, in central Quang Nam Province, turned to using candles and lanterns in its fourth year of participation.

Earlier, local people and visitors joined hands in cleaning and collecting rubbish along the An Ban and Cua Dai beaches as well as in the ancient quarter while also planting trees in commitment to protecting the environment.

Meanwhile, HCM City bathed in the sparkling light of candles, solar energy and energy-saving lighting systems.

Sponsored by the World Wide Fund for Nature and first implemented in 2007 in Australia, the event aims to raise people's awareness on saving and using power more efficiently to reduce the negative impacts of climate change.