A wave of attacks by Rohingya Muslim insurgents on the security posts on Aug 25 sparked sweeping army counter-insurgency operations in the Muslim-majority north of the state that led to widespread violence and arson and an exodus of some 650,000 Rohingya villagers to Bangladesh.
The United Nations condemned the Myanmar military campaign as ethnic cleansing. Buddhist-majority Myanmar rejected that.
But since Aug 25, the Arakan Rohingya Salvation Army (ARSA) insurgents, who claimed responsibility for the coordinated raids on 30 security posts, have mounted only a few sporadic attacks.
The government did not identify the insurgents involved in the Friday attack on a vehicle taking someone to hospital but the military said in a statement they were "extremist Bengali terrorists ARSA”.
"A vehicle ... was attacked by 20 insurgents from the mountain using homemade mines and small arms," the government said. The military said there were about 10 attackers.
An ARSA spokesman was not available for comment.
There was no mention of any incident on a Twitter account that routinely carries statements from the group.
The Yangon-based Frontier Myanmar magazine quoted a resident of a nearby village as saying sporadic gunfire had been heard at the time of the ambush.
The area is largely off-limits to reporters.
Myanmar and Bangladesh have been discussing a plan to repatriate the Rohingya refugees but more insecurity in Myanmar is likely to raise doubts about how quickly that might take place.
