Myanmar's military has laid landmines that have killed and injured people in and around villages in Kayah, a conflict-affected region near the border with Thailand, Amnesty International said Wednesday.

The human rights groups said its researchers who visited the region found that landmines laid around people's homes and churches have killed at least 20 people and maimed many other civilians.

The researchers interviewed villagers in an area where the army has been fighting ethnic Karenni armed groups after the military seized power from Myanmar's elected government in February 2021.

Various international agreements including the 1997 Ottawa Convention ban the use of antipersonnel mines with the intention of eliminating weapons that have killed and maimed thousands of people around the world, often long after hostilities have ended.

"The Myanmar military's use of landmines is abhorrent and cruel. At a time when the world has overwhelmingly banned these inherently indiscriminate weapons, the military has placed them in people's yards, homes, and even stairwells, as well as around a church," Matt Wells, Amnesty International's Crisis Response deputy director for thematic issues, said in a statement.

Amnesty's report said landmines have been deployed in at least 20 villages in Kayah. The report backed earlier allegations made by ethnic groups.

The Karenni Human Rights Group earlier this month also accused army forces of planting landmines in villages and settlements in Kayah state.

Last month, the United Nations Children's Fund reported that landmines and unexploded ordnance had maimed or killed children in many regions of the country, with the largest number of casualties in Shan state in northeastern Myanmar.

Apart from the immediate danger, planting landmines can prevent people who flee violence from returning to their homes and fields, Amnesty International noted.

It said that ethnic armed groups were warning residents to be aware of the risks.

"The military appears to be systematically laying landmines near where it is based as well as in areas from which it retreats," it said.

Myanmar has been mired in violence and civil unrest since the military ousted the elected government of Aung San Suu Kyi, triggering widespread peaceful protests that were put down with lethal force by the army and police. The nonviolent opposition has since turned into armed resistance, and the country has slipped into what some U.N. experts characterize as a civil war.

Amnesty International has also accused Myanmar's military of carrying out widespread atrocities in the eastern part of the country that constitute war crimes and probably crimes against humanity, saying that civilians from the Karen and Karenni ethnic minorities have been the targets of unlawful killing, arbitrary detention and forcible displacement.