The cabinet on Tuesday approved the cancellation of a longstanding agreement with Cambodia aimed at clarifying maritime boundaries and enabling joint offshore energy exploration, Prime Minister Anutin Charnvirakul said.
The move defies calls from Cambodia to continue with the 25-year-old pact.
The decision to terminate the 2001 memorandum of understanding had been widely expected and follows two rounds of armed clashes between the two countries last year.
Thailand and Cambodia signed two agreements in 2000 and 2001, commonly known as MoU 43 and MoU 44, or 2543 and 2544 in the Buddhist calendar.
The agreements were intended to guide negotiations on contentious land and maritime boundary issues.
MoU 43 remains in force, although Thailand is also considering whether to revoke it.
The cancellation of MoU 44 was one of Mr Anutin’s election campaign pledges.
Earlier this year, he rode a wave of nationalist sentiment fuelled by fierce fighting with Cambodia to become the first Thai prime minister to win re-election in two decades.
“Cancelling the deal is not related to the border conflict with Cambodia, but part of my policy. It has been 25 years and there has been no progress,” Anutin told reporters, adding that Cambodia would be informed of the decision.
Cambodian Foreign Minister Prak Sokhonn expressed regret over Thailand’s decision.
In a statement issued on Tuesday, he said Cambodia would initiate a compulsory conciliation mechanism under the United Nations Convention on the Law of the Sea, or UNCLOS.
He added that Thailand’s termination of the agreement would not affect Cambodia’s lawful rights over maritime areas.
Thai officials have said future negotiations would be based on provisions under the Law of the Sea convention.
Despite multiple rounds of talks, MoU 44 has made little progress since it was signed.
The process has been repeatedly derailed by political instability in Thailand, intermittent disputes between the two neighbours and strong opposition from Thai nationalist groups.
A ceasefire has been in place between Thailand and Cambodia since late December.
It followed two eruptions of fighting along large stretches of their 817-kilometre border, the first of which ended after intervention by United States President Donald Trump.
Both sides have accused the other of triggering the clashes.
The fighting killed close to 150 people and displaced hundreds of thousands.
