Suspected Boko Haram militants launched four attacks over 24 hours on villages in Niger, Chad and Cameroon, killing, at least, seven people, security and administrative sources said on Wednesday.

The Islamist militants are mostly based in northeastern Nigeria but have become a major threat to wider regional security by carrying out attacks in the lawless Lake Chad zone where the borders of Chad, Cameroon, Niger and Nigeria meet.

In the most deadly of three attacks since Tuesday, militants killed two soldiers and three civilians in Niger's southern border town of Abadam overnight, the sources said.

About 150km (90 miles) east in Chad, three militants were killed when they detonated suicide bombs after being found out by a group of local people as they sought to embark from an island to a lakeside market in Bol. A fourth set off his bomb but survived.