Japanese police are investigating a business arm of the Japan-based pro-North Korean group Chochongryon for its suspected involvement in unauthorized trading with North Korea.

The police raided the headquarters of the North Korean Chamber of Commerce and Industry in Hyogo Prefecture and arrested its accounting head Kim Yong-bu on charges that he filed taxes for Chochongryon affiliates without a license. Some three-hundred police seized tax-related documents and reports from the headquarters on Wednesday.

Suspecting that Chochongryon affiliates avoided taxes to raise operating funds, Japanese authorities strengthened their probe into the pro-North group partly to pressure North Korea.