ASEAN countries have participated in multinational defence drills before, but these are the first featuring just the bloc, which is battling perceptions of irrelevance on major regional issues such as the turmoil in Myanmar and disputes in the South China Sea.

These are non-combat exercises, however, with member forces training in areas such as humanitarian assistance, disaster relief, rescue operations and joint maritime patrols, according to the host Indonesia.

"By uniting together, we can maintain stability in the region for the favour of the people," Indonesian military chief Margono Yudo told reporters on Batam island.

He said forces from every nation in the bloc including Myanmar are taking part in the five-day ASEAN Solidarity Exercise, but did not detail the extent of Myanmar's participation.

The crisis-hit nation was represented at the exercise's opening ceremony on Batam island by a defence attache.

An Indonesian military official later told AFP on condition of anonymity that Myanmar would only attend the drills as an observer.

Myanmar has been ravaged by deadly violence since 2021, when the military deposed Aung San Suu Kyi's government and launched a bloody crackdown on dissent.

The leaders of its junta have since been banned from ASEAN meetings, and the bloc's efforts to defuse the crisis have been fruitless so far.

Indonesia has also denied that the drills are aimed at countering China's growing assertiveness in the South China Sea, which Beijing claims almost in its entirety.

China has angered Indonesia and other Southeast Asian nations in recent years by entering parts of the waterway they claim.

It has developed artificial islands in the region and outfitted some with military facilities and runways.

Initially, organisers had planned to hold the ASEAN Solidary Exercise in the North Natuna Sea, which Indonesia says is inside its exclusive economic zone.

But China also sends patrols there occasionally to assert its historic claim on the area.

After talks between ASEAN military chiefs in June, the exercise was moved to the South Natuna Sea, avoiding the disputed waters.

Cambodia, China's leading regional ally, had refused to confirm participation at the initial location but is now attending.