The latest incident occurred in a valley in Buthidaung township, near a village that was home to Rohingya Muslim families
Villagers and a lawmaker in Myanmar’s troubled Rakhine state said on Thursday that a military helicopter attacked a group of Rohingya Muslims gathering bamboo, killing five and wounding 13, but a military spokesman declined to comment.
Major-General Tun Tun Nyi said the army would release "true news" about the alleged incident in time.
Myanmar's western Rakhine state came to global attention in 2017, when the army drove about 730,000 ethnic Rohingya across the border into Bangladesh following attacks by Rohingya insurgents on police posts.
The United Nations has accused the army of cracking down on the Muslim minority with "genocidal intent."
More recently, the military has been fighting another armed group, the Arakan Army, which recruits mostly from the ethnic Rakhine Buddhist population.
The latest incident occurred in a valley in Buthidaung township, near a village that was home to Rohingya Muslim families.
"A military airstrike killed five people, including one of our villagers, at around 4pm yesterday," Zaw Kir Ahmed, a community leader from Kin Taung village told Reuters by telephone.
"People in the village don’t dare to go out and are frightened," he added.
Many villages around Buthidaung were razed during the 2017 campaign against Rohingya, though the village that was home to the casualties from Wednesday's attack was spared at that time.
Myanmar’s leaders have vowed to crush all the rebels fighting for autonomy in Rakhine state, an area long scarred by complex ethnic divisions, and authorities have blocked most aid agencies' access to the area, raising fears of more civilian suffering.
Stephan Sakalian, head of delegation in Myanmar at the International Committee of the Red Cross, said teams from the organization had visited Buthidaung Hospital where 13 people were being treated for wounds, some of them in "urgent need of surgery."
"ICRC and Myanmar Red Cross teams are following the situation very closely and offered our services in case of need, including medical supplies or transfer to the Sittwe hospital, as we did two weeks ago with 5 wounded civilians," he said.
Rashid Ahmed, a labourer who spoke by telephone to Reuters, said his elder brother, uncle and nephew had been shot while they were working at Sai Din valley.
"A helicopter attacked them while they were working there, cutting and collecting bamboo," he said. Two other villagers said a helicopter had attacked the group.
Some of the wounded were brought to Buthidaung town, but several died before they reached the hospital, said Maung Kyaw Zan, a lawmaker for the township, adding that five bodies had been recovered.
"When I talked to the wounded people they said the shooting came from the air, there were no clashes on the ground," the lawmaker said.
More than 17,000 people have been displaced by the violence in Rakhine since December, the US embassy said in a statement on Tuesday that urged authorities to allow humanitarian relief for those affected.
"The United States is deeply concerned about the harm to civilians of the ongoing conflict in Rakhine and Chin States between the Arakan Army and the Myanmar military," it said.
"We call on all parties to renew their efforts to end the fighting and work toward a peaceful resolution of the conflict."