Bangkok - Thailand is “fully prepared” to engage in UN-backed mediation initiated by Cambodia over disputed maritime claims, the foreign minister said on June 3, while pledging to safeguard national interests.

Neighbouring Cambodia said on June 2 it had started the dispute resolution process under the United Nations Convention on the Law of the Sea (UNCLOS) over disputed areas in the Gulf of Thailand, where undersea energy reserves are valued at around US$300 billion (S$385 billion).

The move followed Bangkok’s cancellation in April of a 2001 agreement that established a framework for joint oil and gas exploration in areas of overlapping claims, with Thailand’s prime minister citing a long-standing stalemate in implementing it.

Thailand’s Foreign Minister Sihasak Phuangketkeow said in a statement on June 3 that Cambodia’s “rushed decision” to begin compulsory conciliation proceedings under UNCLOS could hinder efforts to “rebuild trust and confidence towards restoring bilateral relations”.

The South-east Asian neighbours have disputed maritime territories and the demarcation of their 800km land border for decades, a legacy of the French colonial era.

After two rounds of deadly border clashes last year, the two sides agreed to a ceasefire in December but have repeatedly accused each other of truce violations.

“Thailand is fully prepared to undertake all necessary actions in accordance with UNCLOS, placing the utmost importance on safeguarding the country’s interests,” Sihasak said in the statement.

Both countries are parties to the convention.

The conciliation process results in non-legally-binding recommendations for the parties to use to negotiate a resolution, according to the Tha...