SHANGHAI (REUTERS) - China has said its army is on high alert after armed groups in Myanmar attacked military and police posts close to their shared border at the weekend and that it is providing shelter for a number of people who fled the fighting.

The official Xinhua news agency said in a report late on Sunday (Nov 20) that three armed groups simultaneously attacked security posts in the border towns of Muse and Kutkai in Myanmar's north-eastern Shan state earlier in the day.

Xinhua, citing unidentified sources, said there were military and civilian casualties but gave no other details.

China's defence ministry said in a statement on its website that it hoped calmness and restraint would be exercised to prevent further escalation.

"The Chinese army is on high alert and will take the necessary measures to safeguard the country's sovereignty and safety, as well as protect the lives and property of Chinese citizens living along the border," the ministry statement said.

The Chinese embassy in Myanmar urged an immediate ceasefire on Sunday and for stability to be returned to the border region, according to a statement on its website.

The Chinese government was temporarily housing an undisclosed number of Myanmar citizens who crossed the border into China to avoid the fighting, the statement said.

Thousands of people have been displaced by decades of fighting between the military and ethnic armed groups in Shan state, which is home to several large groups operating close to the borders with China and Thailand.

China was infuriated last year when five Chinese people were killed when the fighting spilled over into Chinese territory.