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.

Thailand and Cambodia exchanged heavy artillery fire on Friday as their worst fighting in more than a decade stretched for a second day, despite calls from the region and beyond for an immediate ceasefire in an escalating border conflict that has killed at least 16 people.

Armed clashes broke out Thursday between Thailand and Cambodia in long-disputed border areas, rapidly escalating months-long tensions.

More than 30 people have been killed and more than 130,000 people displaced in the worst fighting between the Southeast Asian neighbours in 13 years.