This photo taken by the Kokang Information Network shows Myanmar National Democratic Alliance Army (MNDAA) Major General Peng Deqi (centre R) commanding operations against Myanmar's ruling military near Lashio township in Shan State
This photo taken by the Kokang Information Network shows Myanmar National Democratic Alliance Army (MNDAA) Major General Peng Deqi (centre R) commanding operations against Myanmar's ruling military near Lashio township in Shan State AFP

An alliance of ethnic rebel groups in Myanmar launched coordinated attacks on the military across the country's north on Friday, posing a fresh challenge to the junta as it struggles to quell resistance to its rule.

The military's 2021 putsch sparked renewed fighting with powerful ethnic rebel groups in northern Shan state, home to a planned billion-dollar rail link, part of China's Belt and Road global infrastructure project.

The Ta'ang National Liberation Army (TNLA), the Arakan Army (AA) and the Myanmar National Democratic Alliance Army (MNDAA) launched a "military operation", they said in a statement.

Pro-military Telegram channels said the rebels were attacking 12 towns or settlements across a swathe of Shan state around 100 kilometres (62 miles) across.

The three rebel groups -- which analysts say can call on at least 15,000 fighters between them -- did not immediately provide details on casualties or whether they had taken territory.

A junta spokesman did not immediately respond to an AFP request for comment.

The MNDAA said its fighters had closed the roads from the trade hub of Lashio to Chinshwehaw and Muse on the China border ahead of a "major offensive".

Footage shared on its media channel showed fighters in what appeared to be an abandoned camp, with weapons and boxes of ammunition scattered across the ground. It did not say where the footage was taken.

Fighting around Lashio -- home to the military's northeast command -- and near the towns of Muse, Chinshwehaw and Laukkai was ongoing, local media and residents said.

Laukkai is about five kilometres from the border with China.

"All shops are closed and no one is going out," a resident of Hopang township, around 10 kilometres from Chinshwehaw, told AFP.

"We can hear the sounds of aircraft and gunfire constantly," they said, requesting anonymity for security reasons.

A Muse resident told AFP that locals were staying indoors as soldiers patrolled the streets and that the road from the town to the city of Mandalay -- a major trade route -- had been closed.

A rescue worker in Lashio who requested anonymity for safety reasons told AFP that rebels had begun shelling the military base near the town from 4:00 am (2130 GMT Thursday) and that the military had responded with artillery fire.

All flights to and from Lashio airport had been cancelled on Friday "because of the situation", an airline ticketing agency told AFP.

China's foreign affairs ministry said it was "closely following" the fighting and called on all sides to prevent the situation from escalating.

In 2017, months of fighting between Myanmar's army and ethnic insurgents in the Kokang border region claimed dozens of lives and sent thousands fleeing from their homes -- many to China.

Myanmar's borderlands are home to more than a dozen ethnic rebel groups, some of which have fought the military for decades over autonomy and control of lucrative resources.

Some have trained and equipped newer "People's Defence Forces" that have sprung up since the 2021 coup and the military's bloody crackdown on dissent.

Earlier this month nearly 30 people were killed and dozens wounded in a strike on a camp for displaced people in neighbouring Kachin state.

The Kachin Independence Army (KIA), an ethnic rebel group that controls the area, blamed the junta for the attack.

Last week the junta ordered air strikes and troop reinforcements as it tried to recover outposts it had lost in subsequent fighting with the KIA, the military and rebels said.

A KIA spokesman told AFP he was not sure if its fighters had joined Friday's attacks.