China raised its coal-fired power capacity by 42.9 gigawatts (GW), or about 4.5%, in the 18 months to June, connecting new projects to the grid at a time when capacity in the rest of the world shrank, according to a study published on Wednesday.

China also has another 121.3 GW of coal-fired power plants under construction, U.S.-based research network Global Energy Monitor said in its report, nearly enough to power the whole of France.

The increase followed a 2014-2016 "permitting surge" by local governments aiming to boost growth figures, while formerly suspended projects have also been restarted, Global Energy Monitor said. In the rest of the world, coal-fired power capacity fell 8.1 GW over the same period.

To cut pollution and greenhouse gas emissions, China has promised to drive an "energy revolution" aimed at dramatically reducing its reliance on coal, which met 59% of its total energy needs last year.

But despite a rapid rise in renewable energy capacity and a transition to natural gas for household heating, coal consumption has continued to increase. China approved new 40 coal mines in the first three quarters of 2019.

China's total coal-fired power capacity stands at more than 1,000 GW. Global Energy Monitor said it needed to close more than 40% of that to meet greenhouse gas reductions required to keep global temperature rises well below 2 degrees Celsius.

"China's continued expansion of its coal fleet is not inevitable," it added. The government could strengthen policies discouraging coal plants, support low-carbon power and begin a transition toward clean energy, it said.

Environmental groups have accused Beijing of relaxing efforts to curb coal consumption, pointing to remarks in October by Premier Li Keqiang, who urged China to make greater use of its coal "endowment" by building clean power plants.

While solar and wind power have already achieved price parity with fossil fuels, some Chinese policymakers worry renewables are unreliable. There are also concerns that decarbonisation will hurt coal regions like Shanxi, which has struggled to find alternative sources of growth.

Some also believe future energy shortages could hurt China's attempts to address its slowing economy, said Yang Fuqiang, senior advisor with the Natural Resources Defense Council, a U.S. environment group.

"Right now there is a big argument about whether China needs more coal-fired power or not," he told Reuters. "They think the fourteenth five-year plan (2021-2025) will stimulate economic development and they are a little afraid there won't be enough electricity to support the economy."