United Nations agency said up to 15,000 people may have fled across Myanmar’s border into China in the past month as fighting between Myanmar’s army and ethnic armed groups increased.

Pierre Peron, a Spokesman for the UN Office for the Coordination of Humanitarian Affairs (OCHA) in Myanmar, said aid access to people affected by conflict in the northern states of Kachin and Shan “is getting worse, not better”.

The OCHA said that as well as the estimated 15,000 new refugees, another 2,400 people had been displaced internally in the northern part of Shan state since Nov. 20.

The attacks disrupted trade across the border and China has expressed concern over stray shells and bullets landing in its territory.

Weeks of clashes and the new displacements have damaged Myanmar leader Aung San Suu Kyi’s hopes of securing peace in the long-running conflicts in the mountainous border areas, a goal she has made her administration’s top priority.

Observers feared Suu Kyi’s fledgling civilian administration was unable to rein in the army, which retained political power and is free from civilian oversight.

“Humanitarian access to conflict areas in Kachin and Shan states is currently worse than at any point in the past few years.

“This has seriously affected the ability of humanitarian organisations to provide life-saving aid to tens of thousands of internally displaced and other conflict-affected people,’’ Peron said.

Government forces launched “clearance operations” there after armed men, believed to be from the oppressed Rohingya Muslim group, attacked border police.

The army said it would step up operations in Shan state following the November attacks.

A Myanmar police official, who requested anonymity because he was not authorised to speak to newsmen said that government forces had clashed with armed groups in northern Shan for 170 times in the past month.

According to state media, in a separate offensive to the north, government forces took control of a strategic hill close to the Kachin Independence Army’s headquarters at Laiza on the Chinese border on Saturday.

“Shells reportedly landed near a camp for the internally displaced just outside Laiza on Sunday,’’ the OCHA said, citing unconfirmed reports that it could not verify independently.

It said no casualties were reported but shelters were damaged and about 400 people had to be evacuated.

However a Myanmar government spokesman was not immediately available for comment.