China on Saturday set less ambitious climate change goals for this year than it achieved in 2015, as the world's biggest polluter struggles to wean itself off harmful fossil fuels.

Beijing has said its emissions of the greenhouse gases that cause climate change will carry on rising until "around 2030".

It frequently prefers to point instead to its achievements in energy intensity -- the amount of power used per unit of GDP -- which it has repeatedly reduced in recent years.

Last year it cut it by "at least 5.6 percent", the National Development and Reform Commission (NDRC), the country's top planning body, said in a report to the National People's Congress, the country's Communist-controlled parliament.

But the document set a goal of only a 3.4 percent cut this year.

Similarly, carbon dioxide emissions per unit of GDP went down "at least six percent", the NDRC said, but the 2016 target was set at 3.9 percent.

Other pollutants also had weaker targets for this year than had been achieved in 2015.

China's rise to become the world's second largest economy was largely powered by cheap, dirty coal. But as growth slows, the country has had a difficult time weaning itself off the fuel, even as the pollution it causes wreaks havoc on the environment and public health.

Earlier this week, China reported that its coal consumption had fallen for the second year in a row, with coal use dropping 3.7 percent compared to 2014 levels.

Yet there are widespread doubts over the accuracy of official statistics in China, which critics say can be subject to political manipulation.

It emerged in November that China had been under-reporting its coal consumption for years, prompting a revision of official data that shot the figure for 2012 alone up 17 percent, or 600 million tonnes.

Parts of China are often blanketed with toxic smog, much of it the result of using the fuel in industries such as power generation and steel.

Nearly 300 Chinese cities failed to meet national standards for air quality last year, according to a Greenpeace report.

"We should strive for major progress in the control and prevention of air pollution," Premier Li Keqiang told the NPC's opening session Saturday.

Within five years, he said, city air quality should be rated "good" or better 80 percent of the time.

He pledged that 3.8 million old or high-emission vehicles would be taken off the roads this year.

"Every one of us has an obligation to protect the environment -- we call on every member of society to act and contribute to the building of a beautiful China," Li said.