The United Nations Secretary-General Antonio Guterres has strongly condemned the attacks on Saturday by "unidentified gunmen" on two villages in Tillabery region in western Niger, close to the border with Mali.

In a statement, the secretary-general expressed his deepest condolences to the bereaved families and the people and government of Niger and wished a speedy recovery to the injured.

The UN chief expressed confidence that the Nigerien authorities would spare no effort in identifying and swiftly bringing the perpetrators to justice.

"The secretary-general reaffirms the solidarity and support of the United Nations to the government and people of Niger in their fight against terrorism, violent extremism and organized crime," said the statement.

Around 100 people were reportedly killed in the villages of Tchombangou and Zaroumbareye in western Niger, the latest in a string of civilian massacres.

The attacks occurred Saturday just as first-round presidential results were announced two days earlier.