The huge Mengneng Xilin Thermal Power Plant's third unit, expected to deliver 700 megawatts of power to China's north, was ordered to cease construction in January 2017.

The order came from China's National Energy Administration as part of a government plan to eliminate millions of tons of "overcapacity" caused by a rush of approvals and the construction of "illegal" power plants. It is also part of President Xi Jinping's pledge to reduce the country's reliance on coal and reach peak carbon emissions by 2030.

But even as China reiterated its commitment to reducing emissions last week in New York, earlier this month at least three large, new coal-fired power stations appeared to be either operating or under construction in Inner Mongolia in northern China -- including Mengneng Xilin.

On the outskirts of the Inner Mongolian city of Xilinhot, smoke could seen swirling from a number of power plants, while others appeared to be busily under construction.

Greenpeace senior global policy adviser Li Shuo said that there had been pushback from provinces and business leaders after the government's 2017 suspension, leading to a number of new coal plants being quietly approved.

The reasons are economic, Li said. China's economy has been looking increasingly shaky after decades of unprecedented growth, driven by a global slowdown and trade competition with the United States. China's quarterly economic growth slowed to 6.2% at the end of June, the lowest level in three decades.

"This has actually been the norm that we have observed over the past few years. Whenever there is downward pressure on an economic front, there is a tendency or desire from the industry and policymakers to unleash large-scale infrastructure projects," Li said.

"Inner Mongolia is ... really the hotspot of the climate battle in this country."

CNN reached out to both the National Energy Administration and the National Development and Reform Commissions, as well as the owners of the power plants, for comment but has not received a response.

Li Fulong, director of development planning of the National Energy Administration, told journalists at a news conference earlier this month that China is a responsible nation that would keep its climate promises. But he stopped short of saying China would halt ongoing or future plant constructions.

"We have developed clean and efficient coal-fired generating units, that have large capacity, high energy efficiency and low pollution emissions," he said. CNN