Yangon, Myanmar: Around a dozen ethnic rebels have been killed in a firefight with Myanmar troops and a further eight captured after renewed clashes in northern Myanmar near the Chinese border, state media said on Sunday.

Myanmar's military has for several days carried out airstrikes and ground assaults on rebel positions in retaliation for an attack last week on a key army headquarters in the Kokang region.

That assault, on the main city of Laukkai, left dozens of soldiers dead in some of the heaviest recent clashes between government forces and rebel groups anywhere in a nation riddled with ethnic insurgencies.

On Saturday morning government troops clashed with Kokang ‘renegade groups’ who had ‘infiltrated’ Laukkai, state-run the Global New Light of Myanmar reported.

After fighting ended in the evening the military seized nearly 100 ‘small weapons... and 13 bodies of the armed group,’ the report said, adding a further eight seriously wounded rebels were detained.

Authorities said unrest flared in Kokang, Shan State, on February 9 shattering nearly six years of relative calm, in a serious blow to the quasi-civilian regime as it looks to forge a historic nationwide ceasefire to end the country's myriad ethnic minority conflicts.

Clear accounts of a week of conflict in the mountainous, remote Kokang area bordering China are hard to ascertain.

An unknown number of people have fled the Kokang unrest, with those of ethnic Chinese origin crossing the border into China, while some have made their way to the northern Shan city of Lashio.

Between 300-400 Burmese refugees from the fighting were expected later Sunday in Lashio, an unnamed official at the Information Ministry told AFP, joining around 500 who have arrived since Friday.

The Kokang rebels have been joined by the Ta'ang National Liberation Army (TNLA)and the powerful Kachin Independence Army (KIA), which have both continued to battle the government's forces in other areas of Shan and nearby Kachin states.

It is unclear what provoked the latest round of violence, which coincided with the country's celebrations of its symbolic Union Day Thursday.

Myanmar's information minister Ye Htut has blamed local Kokang rebel leader Phone Kya Shin for the fighting and called on Beijing to reign in any local officials who might be helping the group on their side of the border.

Despite the flare up of violence, the government, the military and a handful of ethnic armed groups signed a commitment Thursday to continue talks, laying out an aim to build a union with ‘federal principles’, but a long hoped for nationwide ceasefire deal remains elusive.

Fighting in resource-rich Kachin, which erupted in 2011 when a 17-year ceasefire crumbled, is seen as a significant barrier to reaching an agreement. It has seen some 100,000 people forced into displacement camps.