Three North Korean officials including Won Kil U, the vice sports minister, have canceled a trip to Japan scheduled for next week despite Tokyo’s earlier decision to allow their attendance at a seminar related to the 2020 Olympics, sources familiar with the matter have said.

The officials conveyed their decision to Japan without providing an explanation, the sources said Friday.

The Japanese government had made an exception in greenlighting their travel to the capital, since Tokyo has in principle banned North Koreans from entering the country as part of unilateral sanctions against Pyongyang over its nuclear and missile programs.

According to the sources, North Korea may also cancel its planned participation in the World Judo Championships starting Aug. 25 in Tokyo.

The three North Korean officials were scheduled to arrive in Japan on Monday to attend a seminar for officials from National Olympic Committees in Tokyo from Tuesday to Thursday.

In November last year, Japan allowed North Korea’s sports minister Kim Il Guk to attend a general assembly meeting of the Association of National Olympic Committees in Japan.