BEIJING, June 9 (Reuters) - China, the world's largest coal buyer, cut imports of the fuel by 18% year-on-year in May, customs data showed on Friday, as low-priced domestic coal chipped away at overseas purchases and renewables cut into coal-fired power generation.

Imports for the month were 36.04 million metric tons, down from 43.82 million tons in May 2024, according to the General Administration of Customs.

The fall marked a third consecutive month of year-on-year decline for China's coal imports, which had previously increased every month since November 2022, excluding January and February, when year-on-year comparisons are affected by the Lunar New Year holiday.

For the first five months of the year, coal imports stood at 188.7 million metric tons, down 8% from 204.9 million tons a year earlier, the data showed.

Domestic prices have remained at four-year lows, cutting into profits for imported coal.

The price for medium-grade coal with a heat value of 5,500 kilocalories per kg averaged 632 ($87.91) for the month of May, according to the Bohai-Rim Bay thermal coal price index.

Domestic coal production has also been on the rise, increasing 7% to 1.58 billion tons for the first four months of the year.

China's thermal power generation, which mostly comes from coal with a small amount from natural gas, fell 4% during January-April while generation from renewables captured the 3% increase in power demand during the four months.