An attack by suspected Islamist Boko Haram fighters have killed some 40 people in two towns of Niger and have set dozens of houses ablaze.
A government official has said the attack marks the latest attempt by the Nigeria-based Boko Haram to strike inside neighbouring countries that have joined the Nigerian military's attempt to quash the group.
Earlier this week, authorities in Chad blamed the group for two suicide bombings in the capital that left at least 33 people dead.
Yakouba Soumana Gaoh, the governor of Niger's Diffa region, said the army was hunting down those responsible for the violence overnight in the towns of Lamana and Ngoumawa.
"The attackers looted stores, burned villages and shot at people who tried to flee," he said.
In April, Boko Haram attacked Niger and killed at least 58 people, saying the assault was in retaliation for Niger's support of the Nigerian military.
In Chad, government military spokesman colonel Azem Bermandoa said an aerial assault had been launched inside Nigeria on Boko Haram positions.
However, Nigeria denied the claim, saying the places reportedly hit are 'most likely to be in the Niger Republic and not Nigeria'.
"Although the terms of the multilateral and bilateral understanding with partners in the war against terror allow some degree of hot pursuit against the terrorists, the territory of Nigeria has not been violated," said major general Chris Olukolade, Nigeria's director of defense information.
Boko Haram's six-year-old uprising, which began in northeast Nigeria, is blamed for the deaths of 13,000 people.
More than 1.5 million have been driven from their homes, some across borders. Boko Haram took control of a large swath of northeast Nigeria until a multinational force this year forced them out of towns and villages. The extremists still engage in cross-border hit-and-run attacks.