Japan and Pacific island nations will discuss a range of common issues they face during a three-day summit due to open in Tokyo on Tuesday.

Japan invites leaders from South Pacific island nations and other countries once every three years for the Pacific Islands Leaders Meeting. This year's gathering in Tokyo will bring together representatives from 18 countries and territories.

Japanese Prime Minister Kishida Fumio will attend an event to welcome their arrival and then will meet with leaders separately on Tuesday and Wednesday. Kishida will also serve as co-chair of Thursday's summit session, where they are expected to discuss issues including climate change, natural disasters and maritime security.

Kishida will announce that Japan is ready to provide satellite meteorological data in real time to help the island nations enhance their disaster preparedness steps, such as tsunami evacuation planning.

Kishida will also call for understanding of Japan's discharge of treated and diluted water from the crippled Fukushima Daiichi nuclear power plant.

The Fukushima Daiichi plant suffered a triple meltdown in the 2011 earthquake and tsunami.

Water used to cool molten fuel has been mixing with rain and groundwater. The accumulated water is being treated to remove most radioactive substances, but still contains tritium.

Before releasing the treated water into the ocean, the plant's operator dilutes it to reduce the tritium levels to about one-seventh of the World Health Organization's guidance level for drinking water.

The outcome of the meetings is expected to be revealed later in a leaders' declaration and action plan.

Japan's government hopes to use the summit as a catalyst to strengthen ties with the South Pacific island countries, amid China's efforts to increase its presence in the region through infrastructure projects.