BORACAY, Aklan - Southeast Asian ministers agreed Tuesday to prevent Beijing from further militarizing disputed areas through a legally binding document seen to manage tensions in the South China Sea.

The diplomats expressed "grave concern" over weapons systems installed on artificial islands built by China, said Philippine Foreign Secretary Perfecto Yasay Jr.

Beijing has ramped up activities in the vital trade route, prompting a naval patrol from Washington, which insists on freedom of navigation and overflight.

"One of the goals is to prevent that militarization," Yasay told reporters after meeting with fellow ministers of the Association of Southeast Asian Nations (ASEAN) here.

Getting China to "demilitarize" and dismantle existing military structures on the reclaimed islands is a major challenge for the regional bloc, particularly claimants Vietnam, Malaysia, and the Philippines.

Yasay said the group would not know exactly how to go about it until a detailed code of conduct with China was completed.

"The structures are there. The only way to have this removed, if China will refuse to remove it, is to remove it by force and we don't want that," he said.

"This is something that we will not engage ourselves in."

China and ASEAN are working to finish the code of conduct framework by June this year or 15 years after they promised to exercise "self-restraint" and not occupy uninhabited islands and other features in the region.

Yasay said the ensuing code should not be "simply a piece of paper that will just further prolong discussions on the matter without getting tangible results out of it."

During the Tuesday meeting, "two to four" ministers brought up the Philippines' arbitral victory over China when Manila had no intention to raise the matter during ASEAN discussions.

Yasay refused to name the ministers, saying only they mentioned the need to "respect" the landmark ruling.

"What they were simply just saying and it is not weird... is that we must respect that jurisprudence laid out in the arbitral tribunal's ruling because that is part of international law," he said.

China claims most of the energy-rich waters, through which about $5 trillion in ship-borne trade passes every year.

China on Friday completed war games involving its own aircraft carrier that unnerved neighbors. The US navy on Saturday said its aircraft carrier strike group had begun routine patrols in the South China Sea.

Three days earlier China warned against that, following an incident in early February when a US Navy P-3 plane and a Chinese military aircraft came close to each other over the South China Sea.

Yasay said ASEAN nations recognized policies under Trump were still "evolving" but hoped he would unveil them within the next few months to provide a "more concrete and clearer picture", especially regarding China.

"We do not know the complete picture of what this foreign policy might be, insofar as its relationship with China is concerned. We're, however, hopeful that the policy that would come out will be positive."

He also said ASEAN wanted a framework for devising a maritime code of conduct between China and the grouping to be completed by June, and Beijing had shown it was keen for it to be finished.

All parties should ensure that the code, which has made little progress since the idea was agreed in 2002, needed to be legally "binding and enforceable", Yasay added. -- with reports from Manuel Mogato, Reuters