BANGKOK: Fighting between Myanmar's junta and ethnic groups Friday raised fears of full-scale civil war and forced more refugees from the northeast across the Chinese border, media and analysts said.

A battle in Shan state between the Kogang rebel group and the government's army began Thursday, breaking a 20-year ceasefire, according to the US Campaign for Burma (USCB), which uses Myanmar's former name.

More than 10,000 refugees have crossed into the Chinese border town of Nansan in southwestern Yunnan province since August 8 and at least one Myanmar policeman was reportedly killed during the fight, the campaign group said.

"People say they have been hearing gunshots and explosions," said Khuensai Jaiyen, editor of the Shan Herald Agency for News.

He said another ethnic group, the United Wa State Army, had now reportedly joined the Kokang forces' fight against the junta and he warned that other groups currently under ceasefire agreements could join in.

"If the Burmese army is returning to a reconciliatory stance it might get better but if not it might be blown into a full-scale civil war," Khuensai Jaiyen said.

He added that the government was trying to create stability ahead of elections scheduled in 2010 but warned "it will be the opposite".

David Mathieson, a Myanmar analyst at Human Rights Watch, agreed full-scale civil war was "a very real fear".

"This could potentially be the flash point that draws in several other groups to the resumption of open conflict," he said.

Myanmar, under military rule since 1962, has signed ceasefires with 17 ethnic armed groups.

Chinese state media reported Friday, citing local officials, that Myanmar nationals were still crossing the border into Yunnan province, without giving a specific figure.

"It's difficult to get a real-time update of that number," Yu Chunyan, a spokesman for the provincial government, was quoted as saying in the English-language Global Times.

The newspaper reported that China had increased the number of armed police along the common border.

Refugees have been settled in a temporary camp, and Chinese officials were providing food and medical care, the state Xinhua news agency reported, citing unnamed provincial government sources.