The United States, Australia, France and Britain will open new embassies in the Pacific, boost staffing levels, and engage with leaders of island nations more often in a bid to counter China's rising influence in the region, sources have said.

The battle for influence in the sparsely populated Pacific matters because each of the tiny island states has a vote at international forums like the United Nations, and they also control vast swaths of resource-rich ocean.

China has spent $1.3 billion on concessionary loans and gifts since 2011 to become the Pacific's second-largest donor after Australia, stoking concern in the West that several tiny nations could end up overburdened and in debt to Beijing.