Myanmar democracy campaigner Aung San Suu Kyi on Sunday said she would not step in to help end worsening conflict between the army and ethnic Kachin rebels without government approval.

"It is up to the government. This case is being handled by the government at the moment," Suu Kyi told AFP when asked if she would get involved in efforts to resolve the fighting, after the army's use of air strikes drew international concern.

The Nobel laureate said she would need an official invitation to join peace negotiations aimed at quelling the raging civil war, which has overshadowed Myanmar's widely-praised political reforms.

Tens of thousands of people have been displaced by the conflict in the far north since June 2011, when a 17-year cease-fire between the government and the Kachin Independence Army broke down.

Myanmar's quasi-civilian regime, which took power in 2011 at the end of junta rule, has reached tentative peace deals with other major ethnic rebel groups, but an agreement with the Kachin has proved elusive.

President Thein Sein, a former general, in December 2011 ordered an end to military offensives against the rebels and continued hostilities have led to doubts over his ability to control the powerful armed forces.

According to the English language state-run New Light of Myanmar newspaper on Sunday, the Myanmar leader has instructed the military not to attack unless in "self-defense."

The report said President Thein Sein urged "mutual trust" and "continued dialogue" in order to bring about peace.

AFP