GENEVA - The UN rights chief on Tuesday said decades of "systematic" abuses against Rohingya Muslims were largely to blame for spiralling violence in Myanmar's Rakhine state, insisting authorities could have prevented the bloodshed.

Zeid Ra'ad Al Hussein expressed alarm at the upsurge in fighting in Rakhine, an impoverished state neighbouring Bangladesh, which has been raging since Friday when Rohingya militants staged coordinated ambushes against Myanmar's security forces.

More than 100 people, including around 80 militants, have been confirmed killed in the fightback, which has seen at least 8,700 Rohingya villagers fleeing for Bangladesh.

"I utterly condemn the violent attacks on security personnel, which have led to the loss of many lives and the displacement of thousands of people," Zeid said in a statement.

But the rights chief stressed that the turn of events was not only "deplorable. It was predicted and could have been prevented." "Decades of persistent and systematic human rights violations, including the very violent security responses to the attacks since October 2016, have almost certainly contributed to the nurturing of violent extremism, with everyone ultimately losing," Zeid said. The Rohingya have in the past largely eschewed violence, but that changed last October when a nascent Rohingya militant group launched surprise attacks on border posts. Myanmar's military reacted with a violent "clearance operation", which the UN has warned could amount to ethnic cleansing. The militants struck again on Friday, attacking around 30 police posts in pre-dawn raids, and killing at least a dozen security force members using knives, homemade explosives and guns.

Zeid on Tuesday called for those who attacked security forces and civilians to be brought to justice, and urged all sides to stop fuelling the violence.

Myanmar's political leadership should "condemn the inflammatory rhetoric and incitement to hatred that is proliferating, including on social media," he said.

Zeid voiced particular concern at "irresponsible" claims made by the government department run by Nobel Laureate Aung San Suu Kyi that international aid workers were complicit in or supporting the attacks.

"I am extremely concerned that the unsupported allegations against international aid organisations place their staff in danger and may make it impossible for them to deliver essential aid," Zeid said.