South Korea's foreign minister has reiterated that Japan also has to act sincerely in order to resolve the issue of wartime labor -- a pending problem in bilateral relations.

Park Jin made the statement at a news conference for foreign media in Seoul on Wednesday.

The foreign minister said the South Korean government is making efforts to find a solution before assets seized from Japanese companies are liquidated.

South Korean courts have ordered Japanese companies to compensate people who say they or their relatives were forced to work for the firms during World War Two.

Park said that once the assets are liquidated, the relations between the two countries are likely to worsen to an unrecoverable level.

He also said he thinks the issue will be resolved if the Japanese side also responds sincerely. But he stopped short of saying what he expects from Japan.

Park also commented on North Korea's nuclear threats. He suggested that Pyongyang appears to have completed preparations for a seventh nuclear test.

Park said the international community would impose severe sanctions if Pyongyang takes provocative action. He said North Korea has to think carefully as its action could harm its own security and further isolate itself.