Updated

Ethnic Kachin rebels in Myanmar said clashes in the country's north continued Saturday despite a government promise to cease fire, casting doubt over hopes that the bloody conflict there could end soon.

Myanmar's military had declared Friday that it would stop attacks against rebels around the town of Lajayang, near Myanmar's northeastern border with China, starting Saturday morning because it had achieved its goal of securing an army outpost there that had been surrounded by insurgents.

An official with the Kachin Independence Army confirmed Lajayang was quiet, but he said fighting was taking place in at least three other rebel positions in the region on Saturday. The official declined to be identified because he is not a spokesman for the rebel group.

The two sides have been fighting for 1 1/2 years, but the latest combat has represented a major escalation because the government employed fighter planes and helicopter gunships in its attacks starting on Christmas Day. Many of the skirmishes have centered on Lajayang, which is about 10 kilometers (6 miles) from Laiza, a town that also serves as a political headquarters for the guerrillas.

The rebel official said fighting Saturday was taking place at Hka Pot and Hka Ya Bhum, both rebel-held hilltop posts located to the north and west of Laiza, respectively. He said fighting was also taking place in Hphakant, more than 160 kilometers (100 miles) further away.

He said the army had launched new offensives in each of the locations, but it was impossible to verify the claims.

Ye Htut, a spokesman for President Thein Sein, accused rebels of attacking a police station in Hphakant before dawn on Saturday, killing two police.

He would not comment directly on the reports of new fighting, but he said the army has "reiterated its commitment to the president's instruction to stop offensives except for self-defense."

The upsurge drew calls from the international community for the two sides to put down their arms and negotiate, but there was no public indication of any direct talks taking place.

Tension with ethnic minorities fighting for greater autonomy in Myanmar is considered one of the biggest major long-term challenges for reformist President Thein Sein, who inherited power in 2011 from the army, which ruled for almost half a century.

The Kachin, like Myanmar's other ethnic minorities, have long sought greater autonomy from the central government. They are the only major ethnic rebel group that has not reached a truce with Thein Sein's administration.

A cease-fire that held for nearly two decades broke down in June 2011 after the Kachin refused to abandon a strategic base near a hydropower plant that is a joint venture with a Chinese company. The conflict has forced about 100,000 Kachin from their homes since then, and many are in camps near Laiza, where they have been digging bomb shelters and bunkers out of fear of air and artillery attacks.