Dec imports at record high of $21.36 bln Dec exports at $22.38 bln as growth decelerates Jan coal export ban seen affecting trade balance 2021 trade surplus of $35.3 bln the biggest since 2007 JAKARTA, Jan 17 (Reuters) - Indonesia"s trade surplus narrowed more than expected in December to $1.02 billion, the lowest in 20 months, as a surge in exports driven by commodities slowedand imports hit a record high, official data showed on Monday. Southeast Asia"s largest economy has been reporting a trade surplus every month since May, 2020, as the coronavirus pandemic supressed local demand while exports rode a boom in prices of commodities like coal, palm oil, copper, tin, steel and rubber. The December surplus was about a third of the $3.13 billion forecast by economists polled by Reuters and was also much smaller than the $3.51 billion recorded in November. December imports hit a record high of $21.36 billion, up 47.93% on a yearly basis and beating the poll"s forecast for 39.40% growth, as overseas purchases of everything from consumer goods to raw materials for the manufacturing industry jumped. "This shows that economic activity is improving ... including consumption," Margo Yuwono, the head of Statistics Indonesia, told a news conference. Meanwhile, export growth was 35.30% on a yearly basis compared with the poll"s expectation of 40.40% growth, with shipments of coal to China slowing as Beijing ramped up domestic output of the fuel. The resource-rich country"s total shipments in December were worth $22.38 billion, the second highest on record for monthly data after November"s $22.84 billion. Economists have warned that a ban on coal exports, implemented since Jan. 1 to avoid widespread domestic power outages, could shift Indonesia"s trade balance to a deficit. Coal exports make up about 14% of Indonesia"s overall exports. The ban has been eased for big miners that have met domestic sales requirements, but is still affecting smaller miners whose output accounts for up to 40% of Indonesia"s total. For the whole of 2021, Indonesia"s exports reached a record high of $231.54 billion, while imports totalled $196.2 billion. The 2021 trade surplus of $35.34 billion was the biggest since 2007.