SINGAPORE, Jan 18 (Reuters) - China"s diesel exports in December sank to their lowest monthly level since March 2015, bringing the 2021 total to the lowest since 2016 at 17.21 million tonnes, data showed on Tuesday. December exports of diesel slumped to 330,000 tonnes, down 78% from a year earlier, amid diminishing export quotas and as refiners curbed runs in response to a slowdown in domestic demand, data from the General Administration of Customs showed. Total refined fuel, including diesel, gasoline, aviation fuel and low-sulphur fuel oil, fell 45% from a year earlier to 3.23 million tonnes last month, the lowest monthly level since July 2020. China diesel exports China diesel exports A diesel crunch triggered by power rationing in the third quarter proved short-lived and the domestic market flipped back into a surplus, analysts said, as reflected in national refinery output, which fell last month by nearly 5% from November and 2% from a year earlier. read more Gasoline exports were 940,000 tonnes, rising from November"s 810,000 tonnes but down 35% from the same period last year. Annual exports fell 9% to 14.54 million tonnes, a three-year low. December jet fuel exports were 590,000 tonnes, down from November"s 940,000 tonnes. Rigid border controls and expanding lockdowns in parts of the country to contain a resurgence of coronavirus infections and fend off the highly contagious Omicron variant dampened demand for gasoline and jet fuel. China"s annual refined fuel exports dropped 2.4% over 2020 to 60.31 million tonnes, as the government tightened export quotas to discourage excessive domestic refinery production. Tuesday"s data showed imports of liquefied natural gas (LNG) at 7.63 million tonnes in December, versus 6.9 million tonnes in November but up just 1.6% versus the year-earlier level as stubbornly high Asian spot prices hurt import appetite. An all-time monthly record high was set in Jan 2021 at 8.49 million tonnes Imports for the whole year totalled a record 78.93 million tonnes, up 18.3% from 2020, making the country the world"s largest buyer of the super-chilled fuel. Piped gas imports last month also set a record at 4.02 million tonnes, up nearly 11% over a year earlier, data showed, as Russian supplies ramped up. Below are details of fuel exports in metric tonnes and imports of LNG in millions of tonnes, with percentage changes as provided by customs. Export Dec-21 y/y change % 2021 y/y change % Gasoline 940,000 -35.2 14,540,000 -9.1 Diesel 330,000 -78.1 17,210,000 -12.9 Jet fuel 590,000 36.5 8,560,000 -14.2 Import LNG 7.63 1.6 78.93 18.3 China LNG imports