The provincial administration said the group had returned to the temporary shelter in Tambon Pang Moo of Mae Hong Son’s Muang district after fighting in Kayah State intensified on Wednesday and Thursday.
Kayah State is on the border with Mae Hong Son.
A source from the Karenni Army said Myanmar troops fired mortar shells at a refugee camp on the Myanmar side, prompting the 591 people who had just returned home to rush back to Mae Hong Son.
The new arrivals pushed the number of Myanmar people seeking refuge in Mae Hong Son to 2,544, the authorities said.
According to official reports, 583 displaced Myanmar nationals are being sheltered in Khun Yuam district, 488 and 882 in two villages in Mae Sariang district.
A high-level source from the Karenni Army said joint Karen resistance groups have stepped up attacks against Myanmar forces in Shan State. The source claimed the groups have seized 17 Myanmar army bases, killed 98 Myanmar soldiers and captured 32, so far.