BANGKOK — Fighting in Myanmar between an armed ethnic rebel group and the country’s military threatened to spill into Chinese territory on Monday, the insurgents said, with reports that shelling had killed three people in the border town of Laiza.
Myanmar’s military in recent weeks has been pushing toward Laiza, the headquarters of the Kachin Independence Army, a rebel group seeking a degree of autonomy from the central government.
Awng Jet, an officer with the Kachin Independence Army, said by telephone the shelling happened early Monday and killed three civilians, including a Christian missionary and a student. Other rebel sources circulated pictures of three bloodied bodies.
Ye Htut, a deputy information minister for the government, expressed skepticism about the attack on his Facebook page and said it needed to be “confirmed independently.”
Fighting between the Kachin rebels and government troops has sharply escalated since Myanmar recently admitted using aircraft to fight the rebels. Government troops have appeared to take at least one hilltop position previously held by the rebels, putting them one step closer to Laiza, which appeared to be the goal of their intensified campaign.
The breakdown of a longstanding cease-fire between the rebels and the military has been a major setback for the government of President Thein Sein, who is trying to guide Myanmar toward democracy after decades of military rule. The cease-fire, which had lasted 17 years, collapsed in June 2011, three months after Mr. Thein Sein came to power.
The army’s decision to pursue the Kachin rebels is risky in part because of the fighting’s proximity to China, which is acutely sensitive to any border problems. The decision also contradicts repeated statements by Mr. Thein Sein that the government is seeking peace with the rebels, as it has with other ethnic groups.
China sent an unspecified number of troops to the border last week to survey what the Chinese state news media called an “unstable area.” A photographer in the area on Monday said that about 200 members of the Chinese security forces had arrived at the border.
The fighting is taking place in the low-lying, jungle-clad mountains, the ancestral homeland of the Kachin and a terrain that they navigate comfortably. Myanmar’s army, although it fought battles in that part of the country in the decades after independence, does not know the area as well. Some analysts believe this is why the military has resorted to using aircraft. A helicopter used in the campaign crashed on Friday, killing the two pilots and an officer onboard. Kachin rebels said they had shot down the helicopter, but the government blamed engine failure.
The Chinese military and officials in Yunnan, the southern Chinese province that borders Myanmar, have been closely observing the deteriorating situation along the border, according to the Chinese state news media.
Global Times, a state-run newspaper, reported on Friday that Shang Haifeng, the deputy Communist Party chief of Nabang, a township by the border, said the Yunnan military command had established an office in Nabang.
Changjiang Daily, a newspaper in the Chinese city of Wuhan, reported on Friday that the conflict was intensifying and that projectiles had exploded on Wednesday and Thursday afternoons in Nabang, which sits across from Laiza. The report said that Chinese civilians had been evacuated to a nearby location.
China’s handling of the situation is made more complex because ethnic Kachin live on both sides of the border. In recent days, thousands of Kachin (who are called Jingpo in Mandarin) living in Nabang gathered at a border checkpoint to protest the attacks by Myanmar’s army, said Ryan Roco, a photographer who was working in the Laiza area. About 2,000 Kachin also gathered on the Myanmar side of the border to show solidarity with the Chinese protesters, he said.
Mr. Roco said Monday in an e-mail that about 200 Chinese security personnel had arrived at the border between Laiza and Nabang.
Reports from Kachin areas suggest that the fighting is hardening the attitudes of Kachin civilians against the central government, which is overwhelmingly made up of the majority ethnic Burmese. The anger and hatred expressed by many Kachin is deflating hopes for a reconciliation.
Moon Nay Li, a coordinator of the Kachin Women’s Association Thailand, an advocacy group, said she sensed “much less trust toward the government” since the army began pursuing the Kachin rebels. “How can we believe in the peace process and democracy in Burma?” she said.
The Kachin are also directing their anger toward Daw Aung San Suu Kyi, the former dissident who is now the opposition leader in Parliament.
Ms. Moon Nay Li was among the signers of an open letter sent last year by 23 Kachin expatriate organizations to Ms. Aung San Suu Kyi, who is ethnically Burmese and who has said little about the conflict.
In a follow-up to the letter sent last week, the Kachin groups lamented the “confusion and distrust that is being created by your failure to comment in depth on these matters.”
This article has been revised to reflect the following correction:
Correction: January 15, 2013
An earlier version of this story misspelled the name of Myanmar’s deputy information minister. It is Ye Htut, not Thut.