Niger is ruled by a military junta led by General Abdourahamane Tiani, who came to power after a coup in July 2023.

The country is facing deadly jihadist attacks on all sides -- from Boko Haram near Lake Chad in the east, and from groups linked to Al-Qaeda and the Islamic State group in the western Tillaberi region.

In the western area bordering Burkina Faso and Mali, which are also ensnared in jihadist violence, HRW said the Islamist militant group has "summarily executed" more than 127 villagers and Muslim worshippers during five attacks recorded since March.

One of the deadliest attacks took place in a village mosque in Manda on June 21, when the jihadists opened fire on worshippers and killed more than 70 people.

"There were bodies everywhere, one on top of the other," a 77-year-old resident who said she lost three sons in the attack told HRW.

Other testimonies recorded by the global rights monitor mention bodies -- including those of children -- riddled with bullets.

No group has claimed responsibility for the attacks but eyewitnesses blame Islamic State jihadists, who HRW says are identifiable by the red-banded turbans they wear.

Residents also said that targeted communities were threatened by IS fighters and accused of collaborating with the Nigerien army before each attack occurred.

According to testimonies, the army "did not adequately respond to warnings of attacks, ignoring villagers' requests for protection".

"Despite warnings of attacks, the army repeatedly fails to protect villagers," HRW said.

"Nigerien authorities need to do more to protect people living in the Tillaberi region" against "atrocities" committed by armed Islamist groups, said HRW's senior Sahel researcher Ilaria Allegrozzi.

The attacks "violated international humanitarian law and are apparent war crimes", the NGO stated, calling on authorities to "bring those responsible to account".

According to figures collected by the conflict monitoring group Acled and cited by HRW, Islamic State fighters have killed around 1,600 civilians in Niger since the military coup over two years ago.