The bloc's joint exercises were initially slated for the North Natuna Sea, which Indonesia claims as its exclusive economic zone but where Beijing's ships occasionally patrol.

When confronted by Jakarta, China has invoked the so-called nine-dash line, which demarcates an area it claims to have historic rights over but is contested by its neighbours.

China claims most of the South China Sea despite protests from Southeast Asian nations, including Indonesia, Vietnam, the Philippines and Malaysia.

The ASEAN's drills will now take place in the South Natuna Sea between September 18 and 25, Indonesia's military said in a statement, avoiding the contested waters.

ASEAN's members have held naval drills with the United States and China before but they have never staged military exercises as a bloc.

The decision came at a planning conference between rotating ASEAN chair Indonesia and "several ASEAN counterparts", the military said, without disclosing which countries attended or abstained.

China's leading regional ally Cambodia refused to confirm its attendance at the drills after they were initially announced.

The Indonesian military statement on Tuesday said the drills will be attended by military leaders from all 10 ASEAN countries.

Military chief Yudo Margono told reporters earlier this month that the drills would focus on maritime security and rescue, and would not involve combat operations.