More than 6,000 civilians were killed in Myanmar in the first 20 months after the February 2021 military coup, a report published Tuesday by the Peace Research Institute of Oslo said.

"Our data shows that the human toll of the conflict is higher than previously reported, and while the junta is clearly the main killer, anti-junta forces also have large amounts of blood on their hands," Stein Tonnesson, one of the two co-authors of the report, said in a statement.

The report said 6,337 civilians were killed "for political reasons" between February 1, 2021 and September 30, 2022, and 2,614 were injured.

That toll is much higher than others that have circulated, including those from international organisations.

According to the report, almost half of the deaths, 3,003, were attributed to the regime -- the army, police and militias -- while 2,152 were attributed to armed opposition groups.

Twelve were attributed to other civilians not affiliated with either the regime or opponents, and 1,170 to undetermined actors.

"This is a larger number than is normally cited in the media, and yet it is only an estimate, based on reported killings gathered from reliable media reports," the report said.

"The actual total is surely higher since many killings have likely gone unreported".

Alleging massive fraud, the Myanmar military annulled the legislative elections won by Aung San Suu Kyi's party and overthrew her government.

Since then, the junta has carried out a large-scale repression of any opposition, arresting more than 23,000 people according to a local watchdog.