BEIJING - The last large coal-fired power plant in Beijing has suspended operations, with the city's electricity now generated by natural gas, the state news agency reported as smog enveloped the Chinese capital this weekend.

The shuttering of the Huangneng Beijing Thermal Power Plant comes on the heels of China's annual legislative sessions, where Premier Li Keqiang promised to "make our skies blue again" in his state-of-the-nation speech. According to Xinhua, Beijing has become the country's first city to have all its power plants fuelled by natural gas, an objective laid out in 2013 in the capital's five-year clean air action plan.

The Huangneng plant is the fourth to be closed and replaced by gas thermal power centres between 2013 and 2017, cutting nearly 10 million tonnes in coal emissions annually. Xinhua reported the move the night before municipal authorities issued a blue alert for heavy air pollution on Sunday. Smog has cloaked the capital for several days and is expected to continue through the week.

Since last Wednesday' closing of the National People's Congress, the annual meeting of China's rubber-stamp parliament, PM2.5 (harmful particulate) levels have remained between 200 and 330 micrograms per cubic metre -- well above the World Health Organization's recommended maximum average exposure of 25 micrograms per cubic metre in a 24-hour period.

The pollution often vanishes during prominent events like the legislative sessions and the 2008 Summer Olympics as authorities order factories to halt activity and force cars off the road.