The Human Rights Watch organization says some 300 people in the Malian town of Moura died at the hands of  Malian armed forces and the Russian soldiers fighting with them.

The executions represent the worst such incident ever reported during the long fight in Mali, which spans a decade and has drawn France, the U.S., and neighboring Sahel nations into the fight against jihadist groups, the international NGO said.

The Malian government said the attacks on Moura began in late March, with 203 people killed by April 1.

“The killings occurred amid a dramatic spike in unlawful killings of civilians and suspects since late 2021 by armed Islamist groups linked to Al-Qaeda in the Islamic Maghreb (AQIM) and the Islamic State in the Greater Sahara (ISGS), and by Malian government security forces,” said Human Rights Watch.

“Armed Islamists have also killed scores of security force personnel since the beginning of 2022.”

Witnesses in Sofara, Ségou, Mopti, Diabaly, and Belidanédji are among those who confirm the presence of Russian fighters in their communities, despite claims they are serving only in a training capacity.

Russian fighters have had a presence in Mali since at least January, when Malian leader Assimi Goïta announced they were coming to support Mali as France steps away from its security role there.

Human Rights Watch has called on the Malian government to investigate the Moura deaths.

“Abuses by armed Islamist groups is no justification at all for the military’s deliberate slaughter of people in custody,” said Corinne Dufka, Sahel director at Human Rights Watch. “The Malian government is responsible for this atrocity, the worst in Mali in a decade, whether carried about by Malian forces or associated foreign soldiers.”