* Dec exports -13.8 pct y/y; imports -19.2 pct y/y
* 2015 exports, imports post worst performance since 2009
* Govt attributes weak trade in 2015 to oil price decline
* Govt forecasts exports +2.1 pct, imports +2.6 pct in 2016 (Updates throughout after trade ministry forecast statement)
By Christine Kim
SEOUL, Jan 1 (Reuters) - South Korea's exports fell for a 12th straight month in December, capping its worst yearly trade performance since the 2008-2009 global financial crisis, and the government warned there was no quick turnaround in sight.
Low oil prices, slowdowns in China and other emerging economies and weakness in Europe sent global trade plunging this year, dealing a sharp blow to trade-reliant Asian countries which rely heavily on exports of manufactured goods such as petrochemicals and electronics.
South Korea's exports in December fell 13.8 percent in dollar terms from a year earlier, while imports slumped 19.2 percent, the Ministry of Trade, Industry and Energy said on Friday, both lagging forecasts in a Reuters poll and weaker than declines of 4.8 percent and 17.6 percent in November.
Exports for all of 2015 dropped 7.9 percent - the worst since a 13.9 percent decline in 2009 - but are expected to rise 2.1 percent in 2016, the ministry said, while adding there were downside risks to the forecast.
"Sluggish growth in China, sustained low oil prices and stunted growth in emerging economies due to higher rates in the U.S. pose risks to exports this year," the ministry said in a statement.
South Korea is the world's sixth-largest exporter and the first major country to publish December trade figures.
Its sales to China dropped 5.6 percent in 2015, sales to the European Union fell 6.9 percent and shipments to the United States slipped 0.6 percent. The three markets take nearly half of South Korea's total exports.
Oil-related products accounted for 64 percent of the decline in South Korean exports this year, the trade ministry said.
Asia, which accounts for more than one-third of global exports by dollar value, saw a 7 percent drop in exports in the first nine months of 2015, against a 13 percent fall in global exports, World Trade Organisation data showed.
Data on Friday showed activity in China's vast manufacturing sector contracted for a fifth month in a row in December, reinforcing fears the world's second-largest economy may be stuck in a protracted slowdown despite a flurry of stimulus measures.
In December alone, South Korea's shipments to China dropped 16.7 percent on-year in their worst fall since May 2009.