Video shows Burma military 'targeting Kachin rebels'
2 January 2013 Last updated at 09:26 GMT
The BBC has been given video footage which apparently shows Burmese military jets and attack helicopters targeting rebel positions in the northern state of Kachin.
Fighting with the Kachin rebels resumed in 2011, after a 17-year truce.
The footage, shot by the humanitarian group Free Burma Rangers, along with witness accounts, suggests that the Burmese army is going beyond President Thein Sein's public instructions that they should only fight in self defence.
Jonah Fisher reports.