The Japanese government plans to reach out to North Korean officials next week in Mongolia to propose a summit between Prime Minister Shinzo Abe and the North's leader Kim Jong Un, government sources said Wednesday.

Abe has said he is willing to meet Kim "without conditions," softening his previous stance. He had said it would be a prerequisite for a summit that North Korea moves closer to returning Japanese nationals abducted by its agents in the 1970s and 1980s.

U.S. President Donald Trump, who has met Kim twice for negotiations over the denuclearization of the Korean Peninsula, said during a visit to Tokyo this week that he supports an Abe-Kim summit.

According to the sources, Japanese officials hope to speak with North Korean diplomats on the sidelines of a Northeast Asian security conference to be held June 5 and 6 in Ulaanbaatar.

The conference will be a rare opportunity for Japanese and North Korean officials to speak as the countries do not have formal diplomatic ties.

Japan is expected to send a senior official from the Foreign Ministry's Asian and Oceanian Affairs Bureau to the conference, while North Korea may send a vice foreign minister, the sources said.