YANGON - Myanmar's state media said Sunday three army personnel were killed when a helicopter crashed in conflict-torn northern Kachin state, rebutting rebel claims that the aircraft had been shot down.

The military helicopter was on a "security and administrative mission" on Friday when "engine failure" forced it to make an emergency landing, according to the English-language New Light of Myanmar newspaper.

"Some parts of the helicopter were damaged, and two pilots and one flight sergeant who were on board sacrificed their lives for the country," the report said, citing the defence ministry.

Growing fighting between the military and the Kachin Independence Army (KIA) has overshadowed Myanmar's wider political reforms, with the US and UN recently condemning the army's use of air strikes in the state since December.

The rebels claim the helicopter was being used for aerial offensives and troop transportation and said it crashed in their territory after it was hit by KIA fire.

"This is true that they shot down (the helicopter), not an emergency landing," James Lum Dau, spokesman for the KIA's political wing, told AFP. AFP was unable to verify either the government or rebel claims.

Tens of thousands of people have been displaced in Kachin - which borders China - since June 2011 when a 17-year ceasefire between the government and the KIA broke down. The number of casualties is unknown.

The intensification of the unrest in recent weeks is likely to further frustrate efforts to secure a peace deal in the region, observers have warned.

Myanmar has struck tentative ceasefires with most of the other major ethnic rebel groups, but several rounds of talks with the Kachin have shown little tangible progress.

The rebels accuse the government of pushing for a dialogue based only on a ceasefire and troop withdrawals and not addressing longstanding demands for greater political rights.

President Thein Sein defended the army's response to the Kachin rebellion, in comments reported in state media on Friday, saying the Tatmadaw - Myanmar's army - had done everything possible "to make positive contributions to the peace process".

Some experts have cast doubt over the level of control Thein Sein, a former general, exerts over army units in Kachin after an order to end military offensives in December 2011 was apparently ignored.