Foreign ministers from the 11-member Association of Southeast Asian Nations and major partners have meetings in Manila against a backdrop of instability since the US and Iran resumed open conflict, raising fears about energy supplies through the Strait of Hormuz, as well as inflation and global growth.
Risks have increased in recent days, with Yemen's Iran-aligned Houthis announcing a naval blockade on Saudi Arabia, opening a potential new front in the conflict and raising the threat to global energy supplies and trade beyond the Gulf.
"We are deeply concerned that these developments severely undermine the ongoing efforts of key mediators and diminish the prospects for a peaceful resolution through dialogue and diplomacy," the ministers said in a statement on Tuesday after a closed-door meeting.
Southeast Asia, a major oil importer with a combined gross domestic product of $US3.8 trillion, is highly exposed to the supply crunch and has sought to fast-track an ASEAN oil-sharing mechanism to mitigate the impact.
ASEAN has no shortage of challenges closer to home and will on Tuesday hold a consultation on the conflict in Myanmar, as the bloc's peace initiative falters, five years after a military coup that plunged the country into a civil war that has killed an estimated 100,000 people.
Officials are also likely to discuss tensions in the South China Sea, with ASEAN and China still trying to conclude a code of conduct to prevent disputes escalating after nearly 10 years.
Before the gathering, US ally the Philippines accused China's Coast Guard personnel of aggressively striking one of its navy personnel on the head with a baton near the disputed Second Thomas Shoal in the South China Sea on Monday.
China's Coast Guard called that "false" and Beijing on Tuesday said it had summoned the Philippine ambassador.
The US State Department condemned what it described as China's "dangerous and aggressive" actions, in what it called "China's troubling pattern of provocation against lawful Philippine maritime operations".
US Secretary of State Marco Rubio and Chinese Foreign Minister Wang Yi will join the ASEAN-led meeting in the days ahead and could meet on the sidelines.
Also attending will be India, Japan, Australia, South Korea, Russia, Britain and the European Union, among others.
Without naming China, Rubio took a swipe at Beijing in an opinion piece published in Philippine newspapers on his arrival in Manila on Tuesday, reaffirming US commitment to freedom of navigation, but warning such freedom was "by no means guaranteed".
Separately, Australia on Tuesday announced a further $A10 million contribution to a drones package for the Philippine Coast Guard to boost its maritime surveillance capacity, which includes long-range and underwater drone capabilities and training.
