The liaison office will enable discussions with NATO's security partners, such as South Korea, Australia and New Zealand, with geopolitical challenges from China and Russia in mind, the media outlet reported.

Asked about the report, NATO spokesperson Oana Lungescu said the alliance would not go into details of NATO allies' ongoing deliberations.

"NATO has offices and liaison arrangements with a number of international organisations and partner countries, and allies regularly assess those liaison arrangements to ensure that they best serve the needs of both NATO and our partners," she said.

Lungescu said NATO has a close partnership with Japan that continues to grow.

"Practical cooperation includes a wide range of areas, including cyber defence, maritime security, humanitarian assistance and disaster relief, non-proliferation, science and technology, and human security," she said.

Japanese foreign ministry spokespeople were not available for comment. Wednesday is a public holiday in Japan.

The Nikkei Asia report said the proposed office is due to open next year in Tokyo but details such as whether Japan would provide the space or NATO would fund it were under negotiation.

NATO has similar liaison offices in New York, Vienna, Ukraine and other places, it said.

NATO chief Jens Stoltenberg visited Japan in January and pledged with Prime Minister Fumio Kishida to strengthen ties in the face off "historic" security challenges, citing Russia's invasion of Ukraine and China's rising military power.

Japan and NATO are seeking to deepen cooperation on cyber threats, disruptive technologies and disinformation, aiming to sign an individually tailored partnership programme before a NATO summit in July, Nikkei Asia reported.