SEOUL, Jan. 19 (Yonhap) -- South Korea is investigating about 10 companies accused of importing North Korean merchandise in violation of a ban that took effect last year over the sinking of a South Korean warship, an official said Wednesday.

   South Korea suspended all cross-border trade in May last year when a multinational investigation found North Korea responsible for the sinking of the Cheonan earlier that year.

   Forty-six sailors died in the sinking in which the North denies any involvement.

   Unification Ministry spokeswoman Lee Jong-joo said in a briefing in Seoul that authorities are questioning the companies on suspicion of violating the ban by importing marine products, mushrooms and other items from North Korea via China.

   Lee would not say exactly how many companies were undergoing the probe.

   The companies claimed that they had thought the products were originally from China. Lee said the government plans to step up its crackdown on imports from North Korea starting next month in an effort to reinforce the ban.

   The relations between the two Koreas remain at the worst point in years after the Cheonan sinking and the North's Nov. 23 bombardment of the South's border island of Yeonpyeong. Four people died when the North shelled the western island in an attack that the South has vowed to retaliate for.

   Meanwhile, Lee said the amount of goods transported across the border between the Koreas last year hit a record high despite the tension.

   The main reason, she said, was the increase in production at a joint manufacturing complex in the North Korean border town of Kaesong, which remains the only channel of economic cooperation between the countries that fought the 1950-53 Korean War.

   The total amount of cross-border business activities reached US$1.91 billion last year, a 13.9 percent increase compared to US$1.68 billion in 2009, Lee said. Activities involving the Kaesong complex accounted for US$1.44 billion, a year-to-year increase of 53.4 percent, she said.

   samkim@yna.co.kr
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