Dozens of female prisoners were injured in a fierce firefight between rebels and soldiers in northeastern Myanmar following an attack on a government convoy, state media said Tuesday.

The Global New Light of Myanmar said the military launched airstrikes after ethnic Kokang fighters attacked vehicles carrying local people, government workers and inmates from a nearby prison, in the latest assault on civilians trying to escape deadly clashes in Shan state.

It said 44 female prisoners as well as a staff member from the correctional department and a soldier were injured in the fighting Monday in the Kokang region bordering China.

Myanmar last week declared a state of emergency in Kokang in response to the conflict, which began on February 9 and has also sparked alarm in Beijing.

The unrest has virtually emptied the main Kokang town of Laukkai, the epicentre of the fighting, with streets in the once-bustling frontier community transformed into a battleground.

At least 30,000 civilians have fled into southwest China, while tens of thousands more are believed to have been displaced on the Myanmar side of the border.

The Myanmar Red Cross has come under attack twice in recent days while ferrying civilians from the Laukkai area towards the Shan town of Lashio outside the conflict zone. The incidents have drawn condemnation from the United Nations.

Five people were wounded when a vehicle for the aid group, which is separate to the International Committee of the Red Cross, came under fire Saturday -- just four days after an earlier attack on a humanitarian convoy left two injured.

Myanmar has blamed the rebels for the assaults on the aid vehicles -- a claim denied by the Myanmar Nationalities Democratic Alliance Army (MNDAA), the main Kokang insurgent group.

Representatives of the MNDAA could not immediately be reached for comment on Tuesday.

Despite continuing battles Monday, state media said the army had restored "stability" to Laukkai town itself.

It is unclear how many people remain in the remote Kokang region, which is almost cut off from help by aid groups and under martial law. There are no official figures on the civilian death toll.