Japan is considering direct talks with North Korea, the government said Wednesday, adding momentum to the cause after a top level aide to the prime minister made a surprise trip to Pyongyang.

Bilateral talks are on the table as Tokyo seeks to salve the running sore of abductions of its nationals by North Korean spies in the 1970s and 1980s, an issue that inflames public opinion at home.

But any move to break with Washington and Seoul, who have both stressed the need for a united approach to Pyongyang, could rankle.

"As we are seeking all possibilities, of course such a thing is an option," Chief Cabinet Secretary Yoshihide Suga told reporters when asked about resuming talks suspended last year when North Korea announced a rocket launch.

The comment came after Prime Minister Shinzo Abe vowed Sunday to seek talks with Pyongyang on the issue and after adviser Isao Iijima returned from North Korea following a four-day visit.

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.

The trip 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.

South Korea dubbed the trip "unhelpful" to efforts to forge a united front against Pyongyang.

Glyn Davies, the US special representative for North Korea policy, cautioned that Pyongyang was trying to "split" the international community.

Washington would like to see the resumption of six-party talks, which involve the two Koreas, the US, Japan, China and Russia, and are intended to denuclearise the Korean peninsula.

Abe has set great store by seeking a "comprehensive solution" to the abduction issue, along with Pyongyang's nuclear and missile ambitions.

Iijima was a senior aide to Junichiro Koizumi and accompanied his visits to Pyongyang in 2002 and 2004 as Japan's prime minister for talks with then-North Korean leader Kim Jong-Il.

During Koizumi's 2002 trip, North Korea admitted its agents kidnapped Japanese nationals in Cold War years to train spies in Japanese language and customs.

Several of those snatched were allowed to return to Japan along with children who were born in the North, but Pyongyang said the rest of them had died, although many in Japan were not convinced.

Japan will not give "any humanitarian aid" to the impoverished North unless the "abduction victims safely return home", Keiji Furuya, Abe's minister in charge of the abduction issue, told a news conference on Wednesday.

"We will do everything possible to get back all the abduction victims," he said, referring to the possibility of talks.