BANGKOK -- Heavy fighting between Myanmar government troops and Kachin ethnic rebels on Sunday underlined the failure of a government cease-fire that had been announced for the weekend.
Although Kachin sources and an independent observer on the front lines said the government had stopped their airstrikes, the Myanmar military continued to pound rebels using rocket-propelled grenades, heavy artillery and advancing ground troops on both Saturday and Sunday.
As has happened several times during the year and a half of fighting in northern Myanmar, there was a marked difference between the pronouncements of the government and the fighting on the ground.
This was starkly illustrated over the weekend. President Thein Sein wooed foreign donors at a major conference in the Myanmar capital, Naypyidaw, on Saturday, telling them he was working to achieve "genuine peace in the country."
"In order to ensure peace and stability in the country, we must engage in peace-building activities together with all ethnic armed groups," he told the conference, which was attended by representatives from more than two dozen countries. "On the basis of the principle of unity in diversity, we will have to embrace our differences."
Yet the battlefield was hardly quiet as Mr. Thein Sein spoke. Ryan Roco, a U.S. photographer at the front lines, said Myanmar troops shelled Kachin positions throughout the weekend and appeared to be moving to cut off a road leading to Laiza, the headquarters of the Kachin Independence Army.
Awng Jet, an officer with the Kachin rebels, said by telephone that there was "heavy fighting" in and around Lajayang -- the very place where the government announced Friday that the cease-fire would take effect.
On Saturday, a Myanmar government spokesman acknowledged the fighting but said that troops were simply defending themselves.
The Myanmar military is tantalizingly close to Laiza -- about 8 kilometers, or 5 miles, away -- and Kachin rebels are bracing for an assault on the town, which sits on the border with China.
On Sunday, Mr. Thein Sein said that although the army was "within arm's length" of Laiza, "we have announced that we will not overrun them."
Representatives of other ethnic groups have become increasingly cynical about the Myanmar government's statements, especially since the cease-fire this weekend failed to take hold.
The United Nationalities Federal Council, a grouping of ethnic groups, issued a sharply worded statement Sunday saying that "only the most gullible people would believe" that the army is acting in self-defense, as the government has claimed.
The statement also questioned the utility of a cease-fire that was breached immediately after it was supposed to come into effect.
"It is clear that the so-called unilateral cease-fire is designed to appease the international community, the U.S., U.K., China and Japan, which have called for the immediate cessation of hostilities," the statement said.
The statement echoed some of the concerns expressed by the Wa ethnic group in a separate statement issued this month. The Wa, who have a significant arsenal and tens of thousands of men under arms, warned of a return to "civil war."
Ye Htut, the government spokesman, declined to comment Sunday. But Min Zaw Oo, the director of the cease-fire negotiation program at the Myanmar Peace Center, which is helping to lead the government's reconciliation efforts, said Kachin snipers were provoking government troops. Government troops are in close proximity to the rebels and "both sides have to talk about how to keep away from each other," he said.
"But this issue can only can be resolved at the table, not in battle," he said.
Winning the trust of the minority groups, who make up about one-third of the country's population of 55 million, is crucial for Mr. Thein Sein as he moves the country from its repressive past to a more democratic future. Ten ethnic groups have signed cease-fire deals with the government, but there are no long-term political agreements. There appears to be a yawning gap between the federal system that ethnic groups are advocating and the more centralized vision that Mr. Thein Sein has so far espoused.
The president told the conference of foreign donors on Saturday that he would start a "political dialogue" with the 10 ethnic groups "in the near future."
As the Kachin fighting continues, Mr. Thein Sein also has China to worry about. China has repeatedly expressed concern about the situation and last week lashed out at the Myanmar government when a shell landed in its territory.
On Saturday, Mr. Thein Sein met with a high-level Chinese delegation that included Qi Jianguo, the deputy chief of the general staff of the People's Liberation Army. (The presence of such a high-level Chinese military officer was omitted from Myanmar state news media accounts, for reasons that were unclear.)
Mr. Qi said he hoped the Myanmar government would "take care of the security needs in Sino-Myanmar border areas, and adopt effective measures to achieve stability there," according to Xinhua, China's state-run news agency.
One of China's concerns is a further influx of refugees if Myanmar troops attack Laiza.
Khun Ja, a Kachin humanitarian worker near the border with China, said there were 12,000 displaced people at camps near Laiza and more than 60,000 in other camps in Kachin State.
There is enough food to feed the displaced Kachin civilians for a month, she said, but aid workers are also struggling to keep people warm.
"The weather is so cold here," Ms. Khun Ja said. "Blankets are all they have -- but that is not good enough."
Wai Moe contributed reporting from Yangon, Myanmar.
This article originally appeared in The New York Times.