Rohingya News Agency - AFP

Three police officers were attacked with machetes in restive northwestern Myanmar on Saturday by assailants who were shot dead, the military has said, amid lethal violence that authorities have blamed on homegrown Islamist insurgents.

Security forces have killed at least 29 people since attacks were launched a week ago on police posts along the Bangladesh border, according to state media.

The government says the raids in the majority-Muslim region were carried out by an Islamist group led by a Taliban-trained extremist who spent months training up to 400 recruits for the attacks with the help of funding from the Middle East.

If true, it could represent an ominous new chapter for Myanmar's Muslim ethnic Rohingya minority, which had so far shown little taste for jihadist ideology despite being one of the most repressed peoples in the world.

The army said assailants armed with machetes on Saturday attacked three police officers in Lake Ai village in Maungdaw, one of the main towns in the restive northern state of Rakhine.

"Security officers shot them (the attackers) dead as they ran away after the attack," the military said in a statement.

The police were apparently not injured, according to media reports.

Troops have poured into Rakhine since the latest violence broke out, locking down an area where most residents are Rohingya.

The violence has raised the spectre of a return to the sectarian unrest in 2012 that left more than 100 dead in Rakhine and drove tens of thousands of Rohingya into squalid displacement camps.

Rights groups say the military has been gunning down unarmed Rohingya on the streets, but the army says troops have been defending themselves against attackers.

Terrified residents have fled Maungdaw, some leaving on foot with possessions stuffed into bags and buckets, while others have been airlifted out by military helicopters.

"I haven't come here for five days because I am frightened," said Mamood Raphee, a Muslim Rohingya who works at Maungdaw's jetty.

"I came here today even though I am afraid. We will have nothing to eat if I cannot get work."

At the nearby border, soldiers told AFP they were too scared to man their posts for fear of more attacksz

Myanmar's presidential office has said the local Islamists were called Aqa Mul Mujahidin and that they "intended to promote extremist violent ideology among the majority Muslim population of the area."

It named their leader as Havistoohar, a man who has appeared in videos that appear to show armed Rohingya men calling for jihad in landscapes similar to the jungles and rice paddies around the Myanmar-Bangladesh border.

AFP was unable verify the authenticity of the videos.

Myanmar brands its Rohingya as illegal immigrants from Bangladesh and denies them citizenship.