Myanmar's military conducted airstrikes on Sunday targeting ethnic rebels in Karen state, as fresh fighting broke out for control of the town of Lay Kay Kaw near the Thai border, according to a spokesperson at the rebel group and media reports.

Thousands of residents in Lay Kay Kaw, which is only about 20km from the Thai border, had already fled fighting in December around the town that has been a refuge for pro-democracy supporters since the army seized power last year.

A spokesperson for the Karen National Union (KNU), which is...