The death toll in attacks on villages in border regions of Niger has risen to more than 100. Attackers struck as first-round presidential results were announced.

Attackers on motorbikes swept through two villages in western Niger, leaving scores dead in each, a local mayor said on Sunday.

The attacks, on the villages of Tchoma Bangou and Zaroumadareye in the jihadi-plagued Tillaberi region, are only the latest in a string of massacres of civilians. They took place as first-round national presidential results were announced.

The mayor of the Tondikiwindi, Almou Hassane, commune that administers of both villages, said the attacks were waged by "terrorists who came riding about 100 motorcycles."

The attackers apparently split into two columns to carry out simultaneous attacks on the two villages, which are seven kilometres (four miles) apart.

"There were up to 70 dead in Tchoma Bangou and 30 dead in Zaroumadareye," Hassane told the AFP news agency, adding he had just returned from the scene of the attacks.

About 75 other people were injured with some requiring treatment in the capital, Niamey, and the town of Ouallam. The villages lie about 120 kilometers (75 miles) north of Niamey and are close to the border with Mali.

The attack is believed to be in retaliation to the earlier killing of two fighters by villagers, after young people from the area tried to form a self-defense group.

The troubled Sahel region, which lies on the borders of Mali, Nigeria and Burkina Faso, is home to extremists groups who have pledged allegiance to al-Qaida and the "Islamic State" (IS) armed group.

Niger has seen a rise in attacks by those groups vying for territory and hundreds of people have been killed over the past year.

Partial election results

The latest atrocity comes as the West African country counts the results of an election held last week.

A partial tally of ballots announced on Saturday put the Nigerien Party for Democracy and Socialism in the lead but a runoff poll in February will be required after the country's ruling party candidate failed to secure enough votes in the first round.

Ruling party candidate Mohamed Bazoum secured 39.6% of the vote, while opposition candidate Mahamane Ousmane won 16.9%.

Ousmane was Niger's first democratically elected president until he was ousted in a coup in 1996. Bazoum is an ally of President Mahamadou Issoufou, who is stepping down after two terms.