It is described as the worst violence in months in the fertile zone.

The state is bisected by religious hatred focused on the stateless Rohingya Muslim minority, who are reviled by many Buddhists and perceived as illegal immigrants.

Recent weeks have seen tensions surge with near daily killings by shadowy groups operating in remote villages, while Myanmar’s army has poured more troops into the area.

In the early hours of Friday more than 20 police posts came under attack by an estimated 150 insurgents, some carrying guns and using homemade explosives.

“One soldier and 10 police sacrificed their lives for the country,” Commander-in-Chief Min Aung Hlaing said in a statement circulated on Facebook, adding 21 militants also died although others made away with guns.

“Fighting is ongoing at police posts in Kyar Gaung Taung and Nat Chaung villages. The military and police members are fighting back together against extremist Bengali terrorists.”

“Bengali terrorists” is the state’s description of the Rohingya militants.

They emerged as a force last October under the banner of the Arakan Rohingya Salvation Army (ARSA), which claims to be leading an insurgency based in the remote May Yu mountain range bordering Bangladesh.

Confirming the unrest an unnamed police officer in Buthidaung town, close to the worst violence, said border posts remained surrounded by militants as day broke in a fluid, dangerous and “complicated situation”.