Soldiers in Myanmar rampaged through several villages, raping, beheading and killing at least 17 people, residents said, in the latest alleged atrocity since the army seized power two years ago.

The bodies of 17 people were recovered last week in the villages of Nyaung Yin and Tar Taing -- also called Tatai -- in Sagaing region in central Myanmar, according to members of the anti-government resistance and a resident who lost his wife. They said the victims had been detained by the military and in some cases appeared to have been tortured before being killed.

Myanmar has been in turmoil since the military's February 2021 seizure of power from the elected government of Aung San Suu Kyi prompted nationwide peaceful protests that security forces suppressed with deadly force. The violence triggered widespread armed resistance, which has since turned into what some UN experts have characterised as a civil war.

The army has been conducting major offensives in the countryside, including burning villages and driving hundreds of thousands of people from their homes. It has faced some of its toughest resistance in Sagaing, in Myanmar's historic heartland.

The soldiers involved in last week's attacks were in a group of more than 90 who were brought to the area by five helicopters on February 23, said local leaders of the pro-democracy People's Defence Forces and independent Myanmar media.

They said the bodies of 14 people, including three women, were found on Thursday on a small island in a river in Nyaung Yin. Three more male victims were found in Tar Taing, including two members of the local resistance. One of the two was dismembered, with his head cut off, they said.

Tar Taing resident Moe Kyaw, 42, survived the attack but said his 39-year-old wife, Pan Thwal, and 18-year-old nephew were among those killed. He said they were among 70 villagers detained last Wednesday by soldiers who herded their captives from their homes to the local Buddhist monastery.

Myanmar's underground National Unity Government -- the main organisation opposed to military rule that describes itself as the country's legitimate government -- said in an online news conference on Monday that the soldiers were from the 99th Light Infantry Division based in Mandalay Region.

A resistance leader said his group attacked the government troops on Wednesday in a failed effort to rescue the detained villagers.

When they went to the small island where the soldiers had taken about 20 villagers they found 14 bodies in three spots, the resistance leader said.

In an earlier incident apparently involving the same army unit, two boys aged 12 and 13 assisting the People's Defence Force were captured by government troops and beheaded after being forced to show the locations of their camps, according to independent Myanmar media.

A separate group, the Sadaung Lighting People's Defence Force, has said that two of its older teenage members were killed and beheaded in fighting at Kan Daw on the same day.

The military government has not responded to the allegations. In the past, it has denied documented abuses and said that casualties occurred in the course of fighting against armed anti-government guerrillas.

Last week, UN High Commissioner for Human Rights Volker Turk accused Myanmar's ruling generals of carrying out "a scorched earth policy in an attempt to stamp out opposition."

His agency said credible sources have verified the deaths of at least 2,940 civilians since the 2021 military takeover.