It's believed that the offices of KNIC - the state-run North Korean Insurance Company have been searched by a joint task force of police and Treasury officials. The raid happened immediately after the EU blacklisted the insurer last month.
The raid is part of an ongoing investigation into whether the firm is being used as a means to make payments to overseas parties for technology for its banned nuclear program.
5 billion won of assets in the company were frozen by the authorities last year.
According to defector Kim Kwang Jin (now an academic in South Korea) KNIC would offer high premiums to overseas reinsurers and then collect foreign currency when disasters struck. Annual revenues were between $50 and $60 million a year before the latest crackdown.