Myanmar's military launched a second day of air strikes on Wednesday, bombing territory controlled by an ethnic armed group on the border with China, a rebel spokesman told AFP.

The strikes come as the military battles an alliance of armed groups across a northern region that is home to Chinese investment and where the junta says it has lost ground.

A military jet struck a site near the town of Laiza in Kachin state at 12:45 pm local time (0615 GMT), Kachin Independence Army spokesman Colonel Naw Bu told AFP.

He said there were no details yet on casualties from the strike, adding that it came a day after a jet dropped three bombs on Laiza, killing one person and wounding twelve others.

On Tuesday soldiers and officers were killed when the KIA attempted to seize a major road in Kachin state, according to the junta-controlled Global Light of New Myanmar newspaper.

The military said it had carried out an "appropriate counterattack" without giving details.

The "neighbouring country had been warned in advance", it said.

In the neighbouring northern Shan state, thousands of people have been reportedly displaced after three other ethnic armed groups launched coordinated attacks on the junta last Friday.

Shan is home to oil and gas pipelines that supply China and a planned billion-dollar rail link, part of Beijing's Belt and Road global infrastructure project.

On Tuesday China's minister for public security met junta chief Min Aung Hlaing in the capital Naypyidaw, Myanmar state media said, for a second day of talks with top junta officials about the clashes.

They discussed attacks by the Myanmar National Democratic Alliance Army (MNDAA) ethnic armed group "on security camps… with attempts to deteriorate peace and stability in the region", the Global New Light said.

'Unprecedented pressure'

The MNDAA, along with the Arakan Army and the Ta'ang National Liberation Army say they have seized sections of key roads to China — Myanmar's biggest trade partner — since the beginning of their Friday offensive.

On Wednesday the groups said they were in "complete control" of Chinshwehaw town on the China border and Hsenwi, which sits on the road to the China border.

The junta did not immediately respond to questions about whether it still controls the towns.

AFP was unable to reach residents in Hsenwi and in Hopang township, about 10 kilometres from Chinshwehaw. 

The ethnic armed groups said the military has suffered dozens of dead and wounded since Friday although AFP was unable to confirm any casualty figures. 

Myanmar's borderlands are home to more than a dozen ethnic armed 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. 

The AA, MNDAA and TNLA  — which analysts say can call on at least 15,000 fighters between them — have fought sporadically with the junta since its power grab in 2021.

The military was under "unprecedented pressure to respond to the sharpest military reverses it has suffered" since the coup, Bangkok-based security analyst Anthony Davis told AFP.

Beijing maintains ties with some ethnic armed groups along its border with Myanmar, home to ethnic Chinese communities who use Chinese SIM cards and currency.

It has previously denied reports it has supplied the armed groups with weapons.

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 KIA blamed the junta for the attack.