BEIJING: Fresh fighting broke out Saturday in Myanmar's northeast between the junta and rebel ethnic forces, whose leader declared they had killed more than 30 government soldiers, Chinese state media said.

The clashes in Myanmar's remote northeast have driven up to 30,000 refugees across the border in recent weeks, the UN has said, causing China to issue a rare admonishment to its neighbour and ally to resolve the conflict.

The Global Times website quoted ethnic Kokang army leader Peng Jiasheng as saying in an interview that his forces had killed more than 30 junta troops and captured another 50. It said he refused to give his location.

The Washington-based US Campaign for Burma (USCB), which uses Myanmar's former name, also said around 30 junta soldiers had been killed with another 40 injured and 20 missing, citing local sources and ethnic media.

Battles that erupted this week in Kokang, a mainly ethnic Chinese region of Myanmar's Shan state, have violated a 20-year ceasefire and analysts have warned the fighting could escalate into full-scale civil war.

The USCB said around 7,000 junta troops were in the region late Friday, where they had had at least eight military encounters with rebel groups over two days.

A bomb was also thrown across the border Friday killing one and injuring several others in a mountainous region of China's southern Yunnan province, reported state-run China Daily, quoting a Chinese Red Cross official.

Refugees were still crossing the border Saturday, said Khuensai Jaiyen, editor of the Shan Herald Agency for News.

"It's not like the other day, we're not hearing of too many but they are still crossing," he told AFP.

Only sketchy details of the fresh fighting in Myanmar emerged, but China's Global Times said one of its correspondents in the area witnessed "fierce" gunfire between the Kokang ethnic army and government forces on Saturday.

The state newspaper said Chinese border guards had been put on alert to prevent the conflict spreading to China.

A resident of China's Zhenkang county on the border, who gave only his surname Xie, told AFP he heard gunfire in the distance early Saturday.

"It was pretty loud. Everybody could hear it. I heard it for about an hour," he said.

A statement from the Chinese foreign ministry on Friday said it "hopes that Myanmar can appropriately solve its relevant internal problems and safeguard the stability of the China-Myanmar border".

It also urged its neighbour "to protect the safety and legal rights of Chinese citizens in Myanmar".

China is one of the few allies of Myanmar's isolated junta, its main source of military hardware and a major consumer of its vast natural resources, despite Western concerns over the military-ruled nation's rights record.

Refugees who had crossed to the border town of Nansan were being housed in tents or other makeshift shelters and authorities were providing them blankets, medical care and other necessities, Chinese state media reports said.

The Global Times said Chinese border defence troops detained a group of unidentified armed Myanmar nationals as they attempted to cross the border at Nansan. It gave no other details.

China's state-run press has otherwise provided only scant coverage of the situation, a sensitive issue for Beijing due to its long-time support of Myanmar's military government.

Win Min, a Thailand-based Myanmar analyst and academic, said tensions had grown in Myanmar because the junta was trying to exert control ahead of the elections in 2010.

He said the army wanted to bring ethnic groups under its command as border guard forces, but many of them, seeking greater autonomy from the junta, were reluctant.

"The Burmese military are showing ceasefire groups that if they don't agree with their plans they are going to fight," he said.