The rule of law must reign supreme in resolving issues in the South China Sea, Datuk Seri Najib Razak said.

The prime minister said he was "concerned and deeply worried" that measures taken by the engaged parties to affirm their declared rights, no matter how small they might be, would only complicate matters and would not be in anyone's interest in the long run.

"We must hold steadfast to the principles of non-use of force and the peaceful settlement of disputes.

"There should not be any action taken to further aggravate the situation and increase tensions," he said when opening the 28th Asia Pacific Roundtable here Monday night.

The text of his speech was read by Home Minister Datuk Seri Dr Ahmad Zahid Hamidi.

Najib, however, expressed confidence that "the bonds of friendship that binds us are stronger and more durable that the differences that divide us".

The parties involved should not stray from the proven path of dialogue and the peaceful resolution of conflicts, he said, adding he remained hopeful that good sense would prevail.

Najib expressed Malaysia's strong commitment towards the recent Joint Declaration of the Asean Defence Ministers on Defence Cooperation towards a Peaceful and Prosperous Asean Community.

He described it as a significant step forward in strengthening the political-security pillar of the Asean Community.

"It's only with the assurance of peace that it would be possible for this region to attract investments, encourage innovation and create jobs for its people," he said.

Najib noted that Southeast Asian nations wanted peace, prosperity and predictability besides being independent, strong and economically vibrant.

"Our aim is to have a region where nations respect each other while observing rules and norms, and where honour and dignity are manifested by peaceful intentions, visionary policies and good leadership.

"We aspire to a region where the strongest guarantees of peace and prosperity lie in nations working together, not against each other," the prime minister said.

Najib also touched on the need to maintain and enhance the habit of cooperation, like the one seen in the search for missing Malaysia Airlines flight MH370, across a whole range of issues.

"Countering the threat of terrorism, for example, requires a great deal of intelligence-sharing and coordination among our security agencies," he said.

Najib alluded to the recent detention by Malaysian police of a foreign nationals believed to be involved in planning terrorist attacks on foreign consulates in India, including the American consulate-general in Chennai.

Elaborating on the disappearance of MH370 with 239 people on board on March 8, Najib said never before had people witnessed such intense cooperation between so many countries in this region.

"Although MH370 has not yet been found - and I'm confident that we will eventually find it - our joint and coordinated efforts have already shown the value of harnessing the collective strengths of countries in times of need," he said.