In a meeting with South Korean Prime Minister Lee Nak-yeon on the sidelines of an economic forum in Russia, Abe reiterated his support for "the agreement between President Trump and Chairman Kim, in particular, the commitment of the North Korean leader towards the full denuclearization of the Korean Peninsula," said a Japanese foreign ministry spokesman.

"Our position is that the international community should push North Korea to fully and expeditiously implement the commitment he (Kim) made to President Trump," Japanese ministry spokesman Takeshi Osuga told AFP.

The meeting took place during an economic forum in the far eastern city of Vladivostok, with the latest round of diplomatic efforts to curb the North Korean nuclear programme high on the agenda.

The White House said Monday that Trump had received a "very positive" letter from Kim seeking a follow-up meeting after they held a historic summit in Singapore in June.

South Korean President Moon Jae-in, who brokered the Trump-Kim summit, will fly to Pyongyang next week for his third meeting with the North Korean leader this year.

The White House said it was "open" to a new summit with Kim.

In June, Trump and Kim signed a vaguely-worded agreement on denuclearisation but little progress has been made since then.

Japan takes a harsh stance towards Pyongyang, which has sent numerous missile tests in the direction of its territory.

"Shinzo Abe expressed his hope that the upcoming North-South summit meeting will lead to concrete actions towards the denuclearization of North Korea," said Osuga.

On Monday, Abe met South Korea's intelligence chief in Tokyo, Suh Hoon, he added.

Abe and Chinese leader Xi Jinping, who is also attending the Vladivostok forum, are expected to hold a meeting on Wednesday, said a Japanese diplomatic source.