BANGKOK, May 8, 2025 (BSS/AFP) - More than 300 Myanmar people fled into Thailand to seek refuge following an assault on the military by ethnic armed groups, Thailand said Thursday, days after the junta extended a post-earthquake ceasefire.

Myanmar has been mired in civil conflict since a military coup in 2021, with the junta battling a coalition of ethnic armed organisations and pro-democracy resistance forces.

Wednesday's attack by the Karen National Liberation Army (KNLA) and its allied Karen National Defence Organisation (KNDO) targeted a military base in Kayin state, about 2.5 kilometres (1.5 miles) from the Thai border, according to the Thai military.

"The attack involved a close-range encirclement of the base and the use of armed drones to continuously drop explosives throughout the day," a statement said.

By Thursday, 327 Myanmar nationals had crossed into Thailand and were sheltering in two temporary sites, including a temple, with Thai military and police providing security and humanitarian aid, officials said. 

Thai forces have ramped up patrols along the border in Tak province to prevent what officials described as a potential "breach of sovereignty by foreign armed forces".

Myanmar's military government and various armed groups opposed to it announced a ceasefire after the March 28 quake to help relief and recovery efforts.

The truce has been repeatedly broken by air strikes by the junta and attacks by armed groups.

The magnitude-7.7 quake near the central city of Mandalay killed nearly 3,800 and left tens of thousands homeless.