The "Garuda Shield" joint training will see militaries from 14 countries -- including Britain, Australia and Japan -- participate in ground drills and beach-landing exercises from August 1-14 in Indonesia's South Sumatra archipelago and the East of Borneo island, the Indonesian Army said.

A US official said an estimated 3,000 soldiers will participate in the event.

That would make it "the largest" edition since Garuda Shield was established in 2009, Albert Tambunan, an Indonesian military spokesperson told AFP Sunday.

This year's expansion of military cooperation signals an increase in defence ties between the US and some Asia Pacific nations, with tensions flaring in the disputed waters.

The region abuts up to the flashpoint South China Sea -- a vital waterway that Beijing claims almost in its entirety, and has been a key point of contention between several Southeast Asian nations and China during annual meetings.

But Ian Francis, chief of the Office of Defense Cooperation at the US embassy in Jakarta, called the expanded war games a "natural outgrowth of Indonesian military's continuing capability and their willingness to work more broadly with partners".

"This really demonstrates that the US has a growing security cooperation relationship with Indonesia," he told AFP.

A full list of participating countries has not yet been released.

The announcement comes after a visit to Jakarta last month by Admiral John Aquilino, who leads the Indo-Pacific command -- which oversees all US military activities in the region.

Indonesia is not officially a claimant in the South China Sea dispute, but the tensions ensnare Southeast Asia's 10-country regional bloc in annual meetings with Beijing.