BEIJING - China's imports of natural gas surged in 2017 as the government encourages use of cleaner energy.

Imports of natural gas rose 26.9 percent year-on-year to 68.6 million metric tons in 2017, data from the General Administration of Customs (GAC) showed.

In December alone, China imported 7.9 million tonnes of natural gas with total value of 19.8 billion yuan (about $3 billion).

The increase is the result of rising domestic demand, in part driven by environmental protection, according to Huang Songping of the GAC.

China is replacing coal-fired boilers with natural gas or electric boilers for winter heating in the north.

Over 4.7 million households in 28 cities have completed the conversion, 3.94 million of them switched in 2017.

The demand for natural gas has prompted state oil companies to look overseas for new gas sources. Sinopec will take the lead in exploration of liquified natural gas (LNG) in Alaska, according to a deal signed during US President Donald Trump's visit to China last year.