At least 150 civilians from Myanmar's Muslim Rohingya minority may have been killed this week in an artillery and drone attack in the western state of Rakhine that survivors suspect was carried out by a major force in the resistance to military rule.

The Arakan Army, the military wing of the state's Rakhine ethnic group, denied responsibility for the assault Monday on Rohingya trying to flee fierce fighting in Maungdaw town by crossing the Naf River into Bangladesh.

A statement issued Friday by an international medical assistance group, Doctors Without Borders, said that in the past week, it has been treating increasing numbers of Rohingya people with violence-related injuries who managed to cross the border into Bangladesh.

The statement said some patients "reported seeing people bombed while trying to find boats to cross the river into Bangladesh and escape the violence. Others described seeing hundreds of dead bodies on the riverbanks”.

Two self-described survivors contacted by The Associated Press blamed the Arakan Army, as did Rohingya activists and Myanmar's military government. The attack, if confirmed, would be one of the deadliest involving civilians in the country's civil war.

Gruesome videos circulating on social media purport to show dozens of bodies of adults and children strewn along a road near the riverside.

Neither the video nor details of the attack can be easily verified due to tight restrictions on travel and ongoing combat in the area.

Pro-democracy guerrillas and ethnic minority armed forces have been attempting to oust the country's military rulers since they seized power in 2021 from the elected government of Aung San Suu Kyi.

However, the fighting in Rakhine has raised fears of a revival of organized violence against members of the Rohingya minority.

In 2017, a military counter-insurgency campaign drove at least 740,000 members of their community to Bangladesh for safety. Almost all still remain there in overcrowded refugee camps, unable to return home because of the continuing instability.

Many Rohingya have lived in Myanmar for generations, but face widespread prejudice and are generally denied citizenship and other basic rights in the Buddhist-majority country.

The Arakan Army, seeking autonomy from Myanmar's central government, began its Rakhine offensive in November and has gained control of nine of 17 townships, along with one in neighbouring Chin state. It has been trying since June to seize the border town of Maungdaw.

It has been accused of major human rights violations before, particularly involving its capture of the town of Buthidaung in mid-May. It was accused of forcing its estimated 200,000 residents, largely Rohingyas, to leave, and then setting fire to most of the buildings there. The Arakan Army denied such allegations, though witnesses have described the group's actions to the AP and other media.

Allegations of abuses by the Arakan Army are controversial because the group's armed force has played a major role in winning battlefield victories for the resistance movement against military rule.

There is much credible evidence of atrocities carried out by the military government's forces, but reported abuses by resistance groups have minimal.

A 17-year-old Rohingya from Maungdaw who survived the artillery and drone attacks said that just after 6 pm Monday, he saw four drones flying from the southern part of Maungdaw toward the riverbank where about 1,000 Rohingya, including himself, were waiting for boats to cross into Bangladesh.

The man, speaking to the AP by phone Friday from Bangladesh on the condition of anonymity to protect his relatives remaining in Maungdaw, said he and other people jumped into the water as the drones dropped three bombs near where he and 12 of his family members had been standing.

Following the drone attack, about 20 artillery shells also hit the crowd, he said, and he estimated that about 150 people, including children and women, were killed in total, and many others wounded.

Unable to get any boat to cross into Bangladesh that night, he and his family returned to their village in Myanmar and went back to the riverbank around 5 pm Tuesday to try again. But fighting broke out at the site between military government soldiers -- who were in civilian clothes -- and the Arakan Army troops pursuing them.

He said the soldiers withdrew from the riverbank after an hour of fighting, but the Arakan Army troops shot Rohingya civilians remaining there at close range. He saw at least 20 Rohingya killed by them, and believes many others trapped in the crossfire also died.

He and just four family members managed to cross to Bangladesh, while eight others were missing in the aftermath of Tuesday's violence.

A 22-year-old Rohingya man who crossed into Bangladesh by boat just two hours after Monday's attack told the AP that he passed about 50-60 dead bodies before boarding the boat, and saw many injured people, including children, asking for water and help or looking for missing persons in the dark.

The man from Maung Ni village, who also spoke on the condition of anonymity for safety reasons, said 30 people including him and 11 family members were carried by a small boat into Bangladesh around 9 pm Monday. He said they were able to escape Friday and make their way into a refugee camp in Bangladesh.

Both men said they believed the Arakan Army was responsible for the attacks, which came from the direction of the group's encampment south of Maungdaw and resembled drone attacks the group has been making daily on the town itself, which is still held by troops of the military government. The Arakan Army also has a reputation for hostility toward the Rohingya community.

Friday's statement from Doctors Without Borders supported the dates, locations and type of wounds described in the two survivors' accounts.

It said that from Sunday to Wednesday, its teams in Bangladesh treated 39 people for violence-related injuries.

“More than 40 percent were women and children, and many had mortar shell injuries and gunshot wounds," it said, noting that the numbers peaked on Tuesday, when 21 wounded people were treated.

The military, through Myanmar's state-controlled press, also blamed the Arakan Army for attacking Rohingya civilians, an offense the military itself was accused of carrying out on a large scale in 2017.

A report Wednesday in the Global New Light of Myanmar newspaper claimed Arakan Army troops raped and killed Rohingya women and girls.

The Arakan Army, in a statement released Wednesday on the Telegram messaging app, denied carrying out Monday's attack. The group said it bore no responsibility for the deaths, which did not occur in an area under its control. The statement also expressed condolences.

It claimed that the military government's soldiers and local Muslims it said were fighting alongside them were preventing civilians from reaching safe locations.

The situation is especially complicated because the military government has been forcibly drafting Rohingya to serve on its side, while several armed Rohingya groups are widely reported to have abducted Rohingya men from refugee camps in Bangladesh to hand them over to serve in the army.