North Korean leader Kim Jong Un's powerful sister said Monday that Japanese Prime Minister Fumio Kishida has requested a summit with her brother, adding any meeting was unlikely without a policy shift by Tokyo.

"Kishida recently conveyed his wish to meet with the Chairman of the State Affairs Commission of the Democratic People's Republic of Korea at the earliest date possible," Kim Yo Jong said in a statement carried by the official Korean Central News Agency.

Confirming the development in Tokyo, Prime Minister Fumio Kishida on Monday called top-level talks with North Korea "important" after Kim Jong Un's powerful sister said Kishida had requested a summit.

"For Japan-North Korea relations, top-level talks are important to resolve issues such as the abduction issue," Kishida said in parliament, referring to kidnappings that took place in the 1970s and '80s. "This is why we have been making various approaches to North Korea at the level directly under my control, as I have said in the past."

Relations between the two countries have long been dogged by issues including compensation for Japan's brutal occupation of the Korean peninsula between 1910 and 1945 and more recently by Pyongyang's firing of missiles over Japanese territory.

The abduction by North Korean agents of Japanese citizens in the 1970s and 1980s -- forced to train spies in Japanese language and customs -- has also long been a major point of contention.

Kishida has said he wants to change the relationship between Tokyo and Pyongyang and last year expressed his wish to meet with North Korea's leader "without any conditions", saying in a speech at the UN General Assembly that Tokyo was willing to resolve all issues, including the kidnappings.

Last month, the North's Kim Yo Jong -- who is one of the regime's key spokespeople -- hinted at a possible future invitation for the Japanese leader to visit North Korea.

She said on Monday that it was "Japan's political decision that matters the most to pave a new charter in North Korea-Japan relationship."

- Kidnapping issue -

"If Japan tries to interfere with our exercise of sovereign rights like it does now and is resolutely preoccupied with the kidnapping issue, which we have no way of solving or knowing about, it will inevitably face the reputation that the Prime Minister's plan is nothing more than aimed at drawing popularity," she said.

North Korea admitted in 2002 that it had sent agents to kidnap 13 Japanese people in the 1970s and '80s who were used to train spies in Japanese language and customs.

The abductions remain a potent and emotional issue in Japan and suspicions persist that many more were abducted than have been officially recognised.

Analysts have long said that contention over the issue could hinder progress towards a summit between Kishida and Kim Jong Un.

Kim Yo Jong said that Kishida "must know that he cannot meet our leadership just because he wants or has decided to or that we will grant him such a meeting just because."

"If Japan sincerely wants to improve the relationship between the two and become our close neighbour to contribute to guarantee peace and stability in the region, it needs to have political courage to make strategic choices befitting to its national interests," she said.

Japan's former prime minister Junichiro Koizumi paid a landmark visit to Pyongyang while in office in 2002, meeting Kim's father Kim Jong Il and setting out a path to normalise relations in which Japan would offer economic assistance.

The trip led to the return of five Japanese nationals and a follow-up trip by Koizumi, but the diplomacy soon broke down, in part over Tokyo's concern that North Korea was not coming clean about the abduction victims.

Kim inspects 'Seoul' tank unit

North Korea's Kim Jong Un inspected a tank unit which once invaded Seoul during the Korean War, state media reported Monday, with Pyongyang's leader calling for ever greater preparations for combat.

Inter-Korean relations are at one of their lowest points in years, with Kim's military recently conducting a string of banned weapons tests, including launching a ballistic missile and staging a ground test of a "new type" of hypersonic missile engine.

Kim visited the Seoul Ryu Kyong Su Guards 105th Tank Division on Sunday, the official Korean Central News Agency said, with images in state media showing him apparently reviewing South Korean attack plans.

"The division... was the first to charge into Seoul and fly the flag of the DPRK on the puppet capitol building," KCNA said, referring to the North by its official name.

The tank unit "performed distinguished feats in many battles during the past Fatherland Liberation War," KCNA said, referring to the 1950-53 Korean War, which ended with an armistice not a peace treaty, meaning the two countries remain technically at war.

Kim oversaw the unit's drill and expressed "great satisfaction" that the tank crews were well prepared and showed "strong will to annihilate the enemy", KCNA reported.

He also called for more "ideological education" to help soldiers continue their good work "rounding off war preparations and beefing up combat capability".

Food shortages are reportedly widespread in the nuclear-armed North, and Kim visited the unit's cafeteria and oversaw the soldiers' meal.

Supervisors should "always pay deep attention to further improving the servicepersons' diet" Kim said, to "ensure the regular supply of meat, vegetables and various other subsidiary foodstuffs in good time".

So far this year, the nuclear-armed North has declared South Korea its "principal enemy", jettisoned agencies dedicated to reunification and outreach, and threatened war over "even 0.001 mm" of territorial infringement.

Seoul is one of Washington's key regional allies, and the United States stations about 27,000 American soldiers in the South to help protect it against Pyongyang.

North Korea this month warned that Seoul and Washington would pay a "dear price" over their recent joint military exercises, and later announced that Kim had guided an artillery unit it says was capable of striking the South Korean capital.