U.S. President Donald Trump's foreign aid freeze has halted vital projects in the South Pacific, aid workers and analysts say, risking lives and hurting U.S. efforts to woo the region.

Disaster-prone, isolated and threatened by rising seas, tropical Pacific island states are some of the most aid-reliant nations on Earth, development agencies say.

They are also at the center of a contest pitting China against the United States, Australia and other allies in a scramble for diplomatic, financial and military influence in the region.