Cambodia's Foreign Affairs Minister Hor Namhong (C) speaks yesterday during an ASEAN meeting in Phnom Penh. Photograph: Pha Lina/Phnom Penh Post

There was a sense of déjà vu at the Peace Palace yesterday as a week of largely closed-door ASEAN meetings kicked off in earnest with the same contentious issue that so dominated April’s ASEAN Summit: a code of conduct for the South China Sea.

Since the South China Sea-dominated talks at the venue three months ago, ASEAN has developed key elements for a COC that would govern the resources-rich waters that China, Taiwan, the Philippines, Malaysia, Brunei and Vietnam claim.

With China present for some of this week’s ASEAN meetings, which include the 45th Foreign Ministers’ Meeting, some are hopeful progress on the issue is imminent.

“Absolutely [this is the week for progress on the COC],” Indonesian Foreign Minister Marty Natalegawa said on Saturday.

“If not now, when?”

Soeung Rathchavy, secretary of state at the Ministry of Foreign Affairs, said China and ASEAN had been informally preparing for COC discussions for some time.

“China [needs to be] involved in the process. We cannot do it without them,” she said.

The precise details of talks are likely to remain hidden – journalists have spent most of the opening three days confined to the venue’s media centre – but questions have been raised over how China’s rivalry with the US, which is also attending, could affect talks.

The US’s recent engagement with ASEAN states, including the Philippines and Vietnam, is seen as a potential source of friction with China.

“Too often in ASEAN, there’s a concern . . . of dangerous strategic competition between the United States and China,” Kurt Campbell, the State Department’s top official for East Asia and the Pacific, said recently.

“It’s our . . . strong determination to make clear we want to work with China.”

Representatives from ASEAN and China met yesterday morning in a closed-door “informal consultation”.

No press conference was given after the meeting and journalists were barred from waiting outside to speak to participants.

Meanwhile, ASEAN ministers said after a Southeast Asian Nuclear-Weapon-Free Zone meeting that a protocol of the similarly named nuclear weapons moratorium, due to be signed on Thursday, would not be signed until later in the year.

To contact the reporter on this story: Shane Worrell at [email protected]

With assistance from Reuters, Bridget Di Certo, Cheang Sokha and Vong Sokheng