Myanmar's army is preparing a major assault on a stronghold of the nation's Kachin rebel minority, an official from the Kachin Independence Army (KIA) told AFP Thursday.
Around 2,000 government forces have moved into place around the northern town of Laiza -- a key rebel base, the official told AFP requesting anonymity.
The apparent troop build-up comes despite calls by UN chief Ban Ki-moon on Monday for an end to violence, which has forced thousands to flee and tarnished the reformist image of Myanmar's new regime.
"They are preparing to attack the KIA base in Laiza... they have reinforced a lot of the troops and sent a lot of artillery but have not attacked yet," the KIA official said, claiming rebel forces number around 3,000.
Myanmar's new nominally-civilian government has agreed ceasefires with several ethnic rebel groups as part of a slew of reforms since it came to power last year.
But violence in Kachin has continued to rage since a 17-year ceasefire was shattered last year. The fighting has not abated despite an order given by President Thein Sein to the army not to attack Kachin State.
The international community has condemned the violence after tens of thousands of people were displaced by clashes between government troops and guerrillas.
Although the UN recently managed to send aid convoys into hard-to-reach parts of Kachin, many refugees remain in dire need of assistance and with the monsoon looming, conditions are expected to become even more desperate.
State media rarely offers information on army operations in the area, but the English-language government mouthpiece New Light of Myanmar has reported a string of alleged KIA attacks in recent days.
The reports accused the KIA of killing a toddler and wounding civilians in their attacks.
But the KIA denied the allegations and said the stories were aimed at paving the way for the military assault.
"In our history we never attack civilians," the rebel official said. "If there is a military base, government offices, it might be true, but trains, bridges and civilian places... we have never attacked such places."
Civil war has gripped parts of Myanmar since independence in 1948. An end to the conflicts and alleged rights abuses involving government troops is a key demand of Western nations which impose sanctions on the regime.
The regime has surprised observers with a series of reforms, including talks with democracy icon Aung San Suu Kyi, who took a seat parliament Wednesday, and the release of hundreds of political prisoners.