A top North Korean diplomat has essentially acknowledged that North Korea and Japan made contact in July in Vietnam, but said no substantial progress was made toward summit talks between the two country's leaders.

The disclosure was made Saturday to Kyodo News by Shingo Kanemaru, the second son of the late Shin Kanemaru, who was a prominent politician and former Liberal Democratic Party vice president who had worked to establish diplomatic relations between the two countries in the 1990s.

Kanemaru, 73, held talks with Song Il Ho, North Korea's ambassador for negotiations to normalize ties with Japan, during a five-day trip to Pyongyang that ended Saturday.