A senior US official has revealed a plan to bolster coordination among the coast guards of the United States, Japan, Australia and India within the four nations' cooperative framework known as the Quad.

The official made the remark ahead of the Quad summit due to be held in Wilmington in the eastern US state of Delaware on Saturday.

Wilmington is US President Joe Biden's hometown. Japanese Prime Minister Kishida Fumio is among the leaders slated to attend the gathering.

The leaders are expected to agree to strengthen cooperation in maritime security. They appear to have China's growing maritime assertiveness in mind.

The official indicated the plan to boost coast guard cooperation among the Quad will be announced in a joint statement to be released on Saturday.

The plan involves a US Coast Guard vessel for the first time allowing personnel from Quad counterparts, including the Japan Coast Guard, on board the ship for limited periods in the Indo Pacific.

The official said the type of cooperation will continue on a rotational basis as appropriate.

The leaders are also likely to exchange opinions on China's activities in the South China Sea, as well as recent moves by North Korea. The official said the group is expected use the strongest expression it has ever used in an announcement to express its concerns.

The Biden administration is also increasingly wary of China's coercive actions against the Philippines' maritime activities in the South China Sea.