Thailand and Cambodia exchanged heavy artillery fire for a second day on Friday as their worst fighting in over a decade intensified and spread to new areas.

Cambodia is seeking to "internationalise the issue to serve its own political objectives", Thailand’s ambassador to the United Nations Cherdchai Chaivaivid told a closed-door UN Security Council meeting.

The fighting between Thailand’s and Cambodia’s militaries has continued for a second day in a row, with the clash progressively escalating in a border battle that has killed at least 16

Thailand warned its border conflict with Cambodia could “escalate into a state of war” as fighting expanded to new areas and both sides exchanged heated rhetoric on a second day of clashes on Friday.

Tensions have bubbled between the two neighbors for months, flaring on Thursday as Cambodia and Thailand exchanged fire.

Thai and Cambodian soldiers have clashed along the two countries' border in a major escalation of a festering dispute over territory that killed least 14 people, mostly civilians.

Thailand and Cambodia exchanged heavy artillery fire for a second day on Friday as border fighting intensified and spread, while Cambodia's leader said Thailand had agreed to a Malaysian ceasefire proposal but then backed down.

Analysts urge Asean to act quickly and facilitate dialogue, but warn the bloc’s efforts may ‘no longer be sufficient’ given limited tools for intervention.