The prime minister of the Cook Islands is among the guests at this year's Group of Seven summit underway in Hiroshima, western Japan.
Mark Brown will ask world leaders to help Pacific nations grow their economies and handle global warming.
Brown chairs the Pacific Islands Forum this year. He told NHK on Friday that building resilience to climate change is a top priority for the bloc, pointing out that "there is always somebody in the Pacific that will be hit by some hurricane or cyclone or some flood damage."
Another issue in the South Pacific is mounting tensions between China, which is trying to expand its influence in the region, and the United States and its allies, which aim to contain it.
Brown welcomes increased interest in the region, but worries about competition there overheating.
He said, "We would like to see our region as a region where development partners can collaborate, to help us achieve our development goals, rather than as an area where each tries to dominate the other."
Guest nations at the summit will join outreach sessions over the weekend.