Rebel commanders say the headquarters of the ethnic Kachin Independence Army's 4th Division in northern Burma has fallen to government forces.

Zaw Raw, the commander of Kachin forces in Shan state, confirmed that government troops took control of the base late Tuesday after rebel forces withdrew in the face of sustained intense mortar fire.

Brigade officers are quoted as saying hundreds of Kachin villagers have fled in search of safety. They say about 25,000 civilians live in the area, near the proposed route for a Chinese-backed oil pipeline.

Zaw Raw told the exile-run Irrawaddy newspaper his forces are continuing to conduct guerrilla operations in several areas of Shan state.

Fighting between the 8,000-man Kachin Independence Army and the government began in June when Burmese forces marched on Kachin areas near where China is building two hydroelectric dams.

It is almost impossible to confirm reports about the fighting. Burma's border areas are largely off limits to foreigners and journalists.

The Kachin Independence Army, like other ethnic militias in Burma, signed a cease-fire with the central government almost two decades ago. But those agreements began to break down in 2009, when Burma demanded that the militias come under central authority and serve as part of a national border guard.