An ethnic Kachin rebel group says it has clashed more than 20 times with Myanmar government troops since the two sides signed an agreement to de-escalate fighting last month.
For decades, Myanmar has faced rebellions from several ethnic groups seeking autonomy.
The Kachin Independence Army is the only major group that has not reached a cease-fire agreement with the government of President Thein Sein, who came to power in 2011 after almost five decades of harsh military rule.
KIA spokesman La Nan said on Sunday there have been at least 21 clashes since the signing of the agreement last month in the Kachin state capital, Myitkyina, to de-escalate fighting and continue a political dialogue.
There was no immediate response from the government.