Leaders of Japan and Pacific Islands nations have jointly expressed their strong opposition to unilateral attempts to change the status quo by force.

Japan invited leaders from 18 nations and territories in the South Pacific for the triennial Pacific Islands Leaders Meeting in Tokyo.

They issued a declaration after wrapping up their discussions on Thursday, the final day of the three-day summit.

The document highlights climate change as the biggest threat. It says that Japan will support efforts to implement more resilient disaster-prevention measures and promote decarbonization.

Amid increasingly assertive maritime activities by China, the declaration stresses the importance of upholding a free and open maritime order based on the rule of law. It states that the leaders strongly oppose unilateral attempts to change the status quo by force.

The document also refers to Japan's discharge of treated and diluted water from the damaged Fukushima Daiichi nuclear plant into the ocean.

It says the leaders have agreed it is important that responses are based on scientific grounds while heeding a report by the International Atomic Energy Agency that confirmed the operation is consistent with international safety standards.

Japanese Prime Minister Kishida Fumio said at a joint news conference that Japan and Pacific Island nations and territories share common values and principles such as the rule of law and democracy.

He said the summit has shown that these nations and territories are determined to raise their trust and cooperative relations to a higher level and to move forward together toward the future.