At least 32 people including 11 security forces were killed as Rohingya militants besieged border posts in northern Rakhine State, Myanmar's army chief said on Friday, in the worst violence in months in the febrile zone.

“One soldier and 10 police sacrificed their lives for the country,” Myanmar 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”.

It is the worst outbreak of violence for months in the coastal state bisected by religious hatred and follows a milestone report by a commission led by former UN chief Kofi Annan urging immediate action to heal the divide.

More than 20 police posts came under attack by an estimated 150 militants in the early hours of Friday, prompting soldiers to fight back, the statement issued by the State Counsellor's office said.

“Many police posts and stations were attacked,” it said, in at least one case using homemade mines.

Confirming the unrest, a police officer in Buthidaung town, close to the worst violence, said border guard posts remained surrounded by militants as day broke in a fluid and dangerous flare up of violence.

“The situation is complicated... the military is arriving,” the officer told AFP on condition of anonymity, adding some of the attackers were armed with guns.

The northern wedge of Rakhine closest to Bangladesh has been in lockdown since October 2016 deadly attacks by militants on border posts sparked a military response that left scores dead and forced tens of thousands to flee.

The UN believes those security “clearances” may have amounted to the ethnic cleansing of the Rohingya, a mainly Muslim minority living in Buddhist Myanmar. The army and Suu Kyi's civilian government vehemently deny allegations of widespread abuses including rape and murder.

After a period of slackening violence, tensions have boiled over in recent weeks with the military moving hundreds of troops into remote village areas.

Annan was appointed by Suu Kyi to head a year-long commission tasked with healing divisions between the Rohingya and local Buddhists. His report urged Myanmar to scrap restrictions on movement and citizenship for its roughly million-strong Rohingya minority, the majority of whom are stateless.

Friday's “attacks coincidentally came after the release of the final report by the advisory commission on Rakhine State led by Dr Kofi Annan,” Suu Kyi's office said.

Myanmar security forces have conducted sporadic operations to flush out suspected militants throughout this year, often resulting in casualties among Rohingya villagers. They have spoken of their fear of being trapped between the security forces and the militants, who are accused of conducting a shadowy assassination campaign against perceived collaborators with the state.

It was not immediately clear if Friday's outbreak of violence was led by the Arakan Rohingya Salvation Army (ARSA), which claims to lead an insurgency based in the remote May Yu mountain range in northern Rakhine.

Recent tensions have been further tweaked after several Buddhists were found dead, prompting some ethnic Rakhine villagers to flee.