A Myanmar ethnic organisation has locked down a town on the porous China border following a Covid-19 spike, it said Thursday, as Beijing battles a Delta-driven outbreak that has spread across the country.

Almost 2,000 cases had been detected in the town of Laiza, said a spokesman for the Kachin Independence Organisation (KIO), a group that controls swathes of territory bordering China's Yunnan province.

The KIO has imposed a lockdown on the remote town of about 20,000 people since November 2 to contain the outbreak, Colonel Hein Wawm told AFP.

People are not allowed to enter or leave the town and residents have been ordered to stay home unless buying food.

Most of the cases were detected in a school, the spokesman said, adding that the group was working to arrange supplies of food to the town.

A surge in cases in Myanmar in June and July spooked authorities on the other side of its 2,000-kilometre frontier with China, where officials are waging a "zero-case" war on Covid-19.

Beijing closed border crossings and increased patrols to prevent a feared influx of Myanmar refugees fleeing post-coup violence.

During the virus wave the KIO inoculated 10,000 people at their Laiza headquarters with Chinese jabs, a spokesman previously told AFP.