Meeting in Singapore, the foreign ministers of the Association of Southeast Asian Nations (ASEAN) welcomed the start of negotiations, while calling for restraint in activities and avoidance of any actions that may complicate the situation.

"We discussed the matters relating to the South China Sea and took note of the concerns expressed by some ministers on the land reclamations and activities in the area, which have eroded trust and confidence, increased tensions and may undermine peace, security and stability in the region," Singapore's Foreign Minister Vivian Balakrishnan said.

Read: Indonesia - Vietnam Discuss South China Sea

Singapore has taken over the role of chairing ASEAN for 2018, and this week hosts meetings of the group's foreign and defense ministers.

China and ASEAN in August adopted a negotiating framework for a Code of Conduct (COC) in the South China Sea in August.

Both sides hailed the move as a sign of progress, with China welcoming the talks as an opportunity to bolster mutual understanding and trust. Critics, however, suspect Beijing of buying time to consolidate its maritime power.

Malaysia, Taiwan, Brunei, Vietnam and the Philippines claim some or all of the South China Sea, one of the world's busiest sea routes. China claims most of the waterway and has been aggressively building and militarizing artificial islands.

Balakrishnan said the resolution of the South China Sea dispute would not be easy, even with the talks for a code of conduct underway.

"It's going to be a very complicated negotiation," he told a news conference. "Territorial claims are not resolved just because you have a COC," he said.

REUTERS