Tokyo (AFP) - A top North Korean diplomat left Saturday for a tour of Europe amid signs reclusive Pyongyang has started to adopt a more active approach to foreign relations, a report said.

Kang Sok-Ju, a secretary of the central committee of the ruling Workers' Party, is scheduled to visit Belgium, Switzerland and other European countries, Japan's Kyodo news agency reported from the North Korean capital, quoting diplomatic sources.

Kang, 75, who was vice prime minister from 2010-2014, could also make contact with Chinese officials in Beijing on the way to or from Europe, Kyodo said.

He is seen to have played a pivotal role in Pyongyang's relations with the rest of the world, including the United States, Japan and China since the 1990s.

North Korea appears to have launched a diplomatic offensive as it is also planning to send Foreign Minister Ri Su-Yong to New York later in September for the United Nations General Assembly, the report said.

If realised, it would be the first time in 15 years that a North Korean foreign minister has visited the United States.Japan has lifted some unilateral sanctions against the communist state as a reward for its decision to reopen investigations into the fate of Japanese who were kidnapped by North Korean agents in the 1970s and 1980s.

Pyongyang admitted to some of the kidnap cases and returned some of the victims in 2002 but Tokyo has demanded it come clean on all the cases. The abduction issue has derailed efforts to normalise ties between the two countries, along with North Korea's nuclear and missile development.

Kang met twice with Japanese wrestler-turned-lawmaker Kanji "Antonio" Inoki who travelled to Pyongyang to stage an unusual martial arts event last weekend.

For Kang, this is his first overseas trip since becoming a secretary responsible for international affairs in the ruling party in April, Kyodo said.