Cambodia has called for an "immediate" ceasefire with Thailand, as the two countries have seen more than 30 people killed, including civilians, in the ongoing border clashes.

Cambodia's ambassador to the UN, Chhea Keo, said his country asked for a truce "unconditionally", adding that Phnom Penh also wanted a "peaceful solution of the dispute".

Thailand's foreign minister Maris Sangiampongsa said on Saturday that Cambodia needed to show "genuine sincerity in ending the conflict" for ceasefire talks to proceed.

At least 32 people - soldiers and civilians - have been killed and nearly 200,000 displaced in the two Southeast Asian countries, who accuse each other of firing the first shots on Thursday.

Fighting continued for a third day on Saturday. Thailand's military said the Cambodians launched attacks in a new area near the coast in the south, but were pushed back by the navy.

Earlier, Thailand reported fighting in its Surin, Ubon Ratchathani and Srisaket provinces, along the border with Cambodia. It has declared martial law in eight districts bordering Cambodia.