Leaders from Southeast Asia and Japan will hold talks this weekend on boosting security ties with an eye on China, as well as Tokyo's contentious efforts on energy cooperation.

Beijing claims almost the entire South China Sea, a vital trade corridor, and its increasingly aggressive behavior in areas also claimed by Southeast Asian nations has stoked regional tensions.

Close US ally Japan, which also has competing territorial claims with China, is upping its military spending and has boosted security cooperation in the Asia-Pacific region.

Japan agreed last month to help the Philippines — which has seen a spate of incidents involving Chinese vessels in recent weeks — secure new coast guard vessels, to supply a radar system and to start talks on a deal for deploying troops on each other's soil.

According to a draft final statement from the summit this weekend seen by AFP, Japan and the Association of Southeast Asian Nations will commit to "(strengthen) security cooperation, including maritime security cooperation".

The leaders are also expected to stress the need for a "rules-based Indo-Pacific region that is free and open", the peaceful settlement of disputes and respect for territorial integrity.

In September militaries from ASEAN nations held their first-ever joint exercises, although host Indonesia insisted they were non-combat drills, focusing on areas such as disaster relief and maritime patrols.

Japan is also expected to use the summit to push energy cooperation, with a meeting of the Asian Zero Emission Community platform scheduled on Monday together with Australian premier Anthony Albanese virtually, officials said.

Tokyo is boosting its renewables sector but it has also come under fire from environmental groups for providing large-scale public finance for fossil fuel projects around Asia.

Japan has also been seeking to push the export of tech aimed at reducing emissions by coal plants, such as co-firing with ammonia and carbon capture. But critics say these methods are unproven and expensive.

"We can't ask all the ASEAN countries to switch to renewable energy drastically because they don't have sufficient technology, they don't have sufficient resources," a Japanese government official said.

ASEAN includes Brunei, Cambodia, Indonesia, Laos, Malaysia, Philippines, Singapore, Thailand and Vietnam. Myanmar is also a member but leaders of its junta have been banned from the bloc's high-level meetings since failing to implement an agreed five-point peace plan following a 2021 coup.