The US, India, Australia and Japan collectively came out in  strong support of an ASEAN-led mechanism to preserve and promote rules-based order in the Indo-Pacific region where China is flexing its muscles.

Senior officials of the four countries, at a meeting in Bangkok in Friday, also highlighted their efforts to maintain universal respect for international law and freedom of navigation and overflight in the region, an official US statement said.

Welcoming ASEAN's efforts to develop an Indo-Pacific outlook, the four countries affirmed their strong support for ASEAN centrality and ASEAN-led regional architecture, as well as their support for other regional institutions, including the Indian Ocean Rim Association and Pacific Islands Forum, it said.

The 10-nation Association of Southeast Asian Nations (ASEAN) is considered one of the most influential groupings in the region and India and several other countries including the US, China, Japan and Australia are its dialogue partners.

In November 2017, India, the US, Australia and Japan gave shape to the long-pending "Quad" Coalition to develop a new strategy for keeping the critical sea routes in the Indo-Pacific free of any influence.

China has been trying to expand its military presence in the Indo-Pacific, which is a biogeographic region, comprising the Indian Ocean and the western and central Pacific Ocean, including the South China Sea.

China claims almost all of the South China Sea. Vietnam, the Philippines, Malaysia, Brunei and Taiwan have counter claims over the sea.

During the meeting, the four nations reaffirmed their shared commitment to preserve and promote the rules-based order in the region.

"Participants also noted their desire to work with like-minded partners and allies to promote a transparent, rules-based approach to trans-boundary challenges," the statement said.

The four countries underscored their intent to continue regular consultations on Indo-Pacific engagement and initiatives together and with other interested nations and institutions.

They underscored their intent to continue close coordination and collaboration in support of sustainable, private sector-led development, maritime security, and good governance, it said.

The Quad coalition also discussed initiatives undertaken by each country to encourage transparent, principles-based investment in quality infrastructure in accordance with international standards and leverage the potential of the private sector.

"They highlighted their efforts to maintain universal respect for international law and freedom of navigation and overflight," the statement said, adding the officials agreed to continue to explore opportunities to enhance cooperation, including in support of regional disaster response, cybersecurity, maritime security, counterterrorism, and nonproliferation.

The ASEAN region along with India accounts for 1.85 billion people, which is one fourth of the global population and their combined GDP has been estimated at over USD 3.8 trillion.

The ASEAN comprises Singapore, Brunei, Malaysia, Thailand, the Philippines, Indonesia, Vietnam, Laos, Cambodia and Myanmar.