The next round of talks between Japan and North Korea will likely be held in late May at the earliest as Tokyo waits to see how Pyongyang reacts to a court decision on the de facto North Korean Embassy building in Tokyo, government sources said.

The Tokyo High Court is expected to issue a ruling after the Golden Week holidays ending May 6 on whether to uphold the Tokyo District Court's approval last month of the sale of the building and its land, which served as the headquarters for the pro-Pyongyang General Association of Korean Residents in Japan. The group, also known as Chongryon, is appealing the ruling.

The next Japan-North Korea talks will thus likely be held in late May or later, given the time needed for preparations, the sources said.

But if North Korea conducts a fourth nuclear test as threatened, Japan will abandon the negotiations in protest, the sources said. Chongryon acts as the North's embassy in Japan because the two countries lack formal diplomatic ties.

In informal talks in Shanghai earlier this month, the North is believed to have asked Japan to let Chongryon continue using the headquarters.

On March 24, the Tokyo District Court approved the sale of the property, which was put up for auction due to financial problems, to Marunaka Holdings, a real estate company.

In late March in Beijing, Japan and North Korea held their first formal talks in over a year. But the envoys have failed to bridge differences over outstanding issues, including the abduction issue.