Within earshot of mortar fire echoing from beyond a ring of hills, a sprawling relief camp in southwestern China is swelling steadily after fighting erupted last week between a rebel ethnic army in Myanmar and government troops just across the border.

In a recent visit by reporters to the rugged area in southwestern Yunnan province, aid workers and those displaced expressed fears of a more violent and protracted conflict than a previous flare-up in the Kokang region in early 2015.

"Every day, more people come," said Li Yinzhong, an aid manager in the camp, gesturing at the mostly Han Chinese refugees from Myanmar's Kokang region trudging through the reddish mud earth around rows of large blue huts where they sleep on nylon tarpaulin sheets.