Japan's prime minister vowed Sunday to seek talks with Pyongyang in a bid to settle the nagging issue of North Korea's kidnapping of Japanese, without risking its alliance with Washington and Seoul.

Shinzo Abe made the comment after a surprise visit to North Korea by one of his advisers last week irritated the United States and South Korea as a possible damper to their efforts to forge a united front against Pyongyang.

"I want to pursue negotiations or dialogue" with North Korea, he told reporters in Fukuoka, southern Japan, according to Japanese media.

"I will definitely try to realize the return home of all the kidnap victims, the search for truth behind the cases and the handover of the abductors during the Abe government," he said.

But he added Japan will also continue seeking a "comprehensive solution" to the abduction issue along with North Korea's nuclear and missile ambitions in concerted efforts with allies.

The adviser, Isao Iijima, returned home on Saturday after the four-day visit to Pyongyang where he discussed with North Korean officials ways to resolve the long-pending abduction issue.

Iijima told North Korean officials that Tokyo "would not make any move" unless they return all Japanese kidnap victims, hand over the kidnappers and resolve all the abduction cases, according to Japanese media citing sources close to him. But the trip has fuelled speculation Pyongyang was trying to cozy up to Tokyo at a time when ties with Washington and Seoul have gone into deep freeze over its nuclear and missile ambitions.

A member of Abe's cabinet on Sunday defended Iijima's trip which he said reflected the premier's resolve to have North Korea come clean on the abductions in the 1970s and 1980s. "Japan has an extremely important case, the abduction issue, which is separate from interests of other countries," Akira Amari, the state minister of economic revitalization, said in a talk show on NHK.