Ten villagers in southeastern Niger were killed by suspects from Nigeria's Boko Haram group, local sources said on Wednesday.
Gunmen arriving on foot late Monday attacked the villages of Fiego, Ngarwa-Lawandi and Ngarwa-Koura near the town of Diffa, a local official said.
"All the victims are men, and all were killed by gunfire," the source said.
Several other sources said the toll could rise as the nearby village of Lada was also attacked.
Maman Kaka Touda, a representative for a Nigerien NGO called Alternative Citizen Space (AEC), said in a tweet "20 people have been killed," including "10 at Lada."
"These attacks have occurred after a long period of calm -- insecurity has returned to the area," he told AFP.
There was no immediate confirmation of the attacks from the government.
The Diffa region, bordering Nigeria, has been battered since 2015 by cross-border raids by Boko Haram and its rival, Daesh West Africa Province.
Last month, President Mohamed Bazoum commended "the improvement in the security situation" in Diffa and said he would visit the area soon.
He also announced that 500 soldiers would be recruited and 500 others given training so that they could be deployed to villages in the region.
Niger is also struggling with attacks on its southwest border, from neighbouring Mali.
Since 2015, thousands have died and hundreds of thousands are listed as displaced, many of them Nigerians who fled Boko Haram attacks on the other side of the border.
The landlocked Sahel state is rated the poorest in the world by the UN's Human Development Index, which assesses 189 countries and territories.
