Japan was relegated to the fifth-largest export destination for South Korea last year with the portion of exports to Tokyo in Seoul's overall outbound shipments dipping to a record low amid the weak yen, data showed Wednesday.

South Korea's shipments to Japan reached US$25.6 billion last year, accounting for 4.9 percent of its overall exports, the lowest level ever, according to data compiled by the Korea International Trade Association.

Last year's figure marks a 20.5 percent drop from a year earlier.

Japan was the fifth-largest export market for South Korea last year, down one notch from the previous year, the data showed.

The portion hit a record high at 38.5 percent in 1973, with Seoul's shipments to Japan reaching $1.2 billion. In 1988, South Korea's exports to Japan topped $10 billion. In 1963, Seoul's exports to Japan exceeded the $100 million mark.

But China has emerged as South Korea's No. 1 trade partner, and the yen's slide against major peers contributed to reduce bilateral trade with South Korea.

"Prices of Korean goods in Japan are too expensive due to the yen's weakness. That's why our exports to Japan have dropped," said Moon Byung-ki, a researcher at KITA.

The researcher also said foreign products made by China and other rivals expanded their presence in the Japanese market, crowding out Korean goods there.

But imports from Japan soared last year. South Korea suffered a trade deficit of $20.3 billion with Japan.

Meanwhile, South Korean firms operating in Japan expect their business conditions to improve this year, a survey showed.

According to the survey on 69 firms by KITA's Japanese office,

38.2 percent said their business environment will improve this year.

Last year, only 15.5 percent offered a rosy outlook for their business conditions in Japan.

The frayed bilateral ties between the two countries, the Japanese yen's weakness and Japan's improving economy would be swing factors for their operations there this year, the survey showed.

The data also showed that 26 percent of South Korea's exports, or goods worth $137 billion, went to China last year, maintaining its status as South Korea's largest export destination.

South Korea logged a trade surplus of $46.9 billion with China last year. But the trade surplus with Beijing narrowed from $55.2 billion in 2014, according to the data.

The U.S. came in second with a 13.3 percent portion, or $69.8 billion worth of exports, followed by Hong Kong with 5.8 percent and Vietnam with 5.3 percent.

Semiconductors were South Korea's No. 1 export item with $62.9 billion shipped overseas, followed by autos and ships and related parts worth $40.1 billion.

Oil was the most imported commodity. South Korea imported $55.1 billion worth of crude oil last year, trailed by semiconductors at $38.3 billion and natural gas at $18.8 billion, the data showed. (Yonhap)