Exports this month are forecast to have shrunk a median 7.0 percent in annual terms, the survey of 11 economists found, deepening a downturn after a 1.3 percent drop in December.

Imports were seen down 5.3 percent year-on-year, turning down sharply from December when it rose 1.2 percent.

Economists expect a darkening outlook for the rest of the year as the global impact of the Sino-U.S. trade war broadens, hitting corporate earnings, business investment and overall economic growth.

Officials from the United States and China will hold high-level talks on Wednesday and Thursday in ongoing efforts to reach a durable deal.

"If the trade conflicts between the United States and China are not settled, we can't rule out the possibility that 2019 annual growth may shrink," said Lee Sang-jae, an analyst at Eugene Investment & Securities.

South Korea, the world's sixth largest exporter, is the biggest manufacturer of chips, and a substantial exporter of ships, cars and petroleum products. It is the first major exporter to report monthly trade data, which gives an early gauge of the health of global trade.

For the first 20 days in January, the shipments from Asia's fourth-largest economy skidded 14.6 percent with exports to China, its biggest trading partner, plummeting nearly a quarter. Imports contracted 9.5 percent during same period.

China's slowing economy has put a dent on neighbouring countries reliant on sales to the Asian giant, such as South Korea, Japan and Taiwan. The latest trade figures from Japan and Taiwan showed the sharpest falls in several years.

Adding to concerns, prices of South Korea's key export items - computer memory chips and petroleum goods - have weakened for months, leading to dismal fourth-quarter earnings for big local chip companies.

The falling price of chips could hurt South Korea's economy, Bank of Korea (BOK) Governor Lee Ju-yeol told a press briefing last week, after the central bank kept its policy rate steady.

In the Reuters survey, respondents forecast January headline inflation at 1.3 percent, unchanged from the previous month and well below the BOK's 2-percent target.

The poll also forecast no growth in industrial output in December from a month earlier, versus the 1.7 percent decline in November.

December industrial output data is set for release at 2300 GMT on Wednesday. Inflation and trade data are scheduled to be published at 2300 GMT on Thursday and 0000 GMT on Friday, respectively.

(Editing by Shri Navaratnam)

By Hayoung Choi and Cynthia Kim