Video from the Burma Free Rangers group -- they say it shows Myanmar government fighter jets in action against rebels in Kachin State.
On Thursday, Myannar's quasi-civilian government said the military had used air strikes against the fighters.
This would be an escalation of the conflict and some will raise questions about the reformist credentials of the government, which has been lauded on the international scene for its moves toward democracy.
The country has also seen a huge inpouring of international investment.
In the background has been ongoing internal conflicts - one with the Kachin rebels - which has lasted for some 20 months.
Rebel sources there have reported aerial bombings, shelling and even the use of chemical weapons since December 28th when the Kachin Independence Army ignored an ultimatum to stop blocking an army supply route.
Myanmar President Thein Sein's administration insists it wants a ceasefire and political dialogue
Myanmar fighter jets attack rebels (0:57)
Jan. 3 - The use of air strikes against rebels by Myanmar's quasi-civilian government has raised questions about its reformist credentials. Simon Hanna reports. ( Transcript )