The United Nations is strongly condemning an attack along Cameroon's border with Nigeria that killed a U.N. independent contractor and four others.

Mohamed Ibn Chambas, the U.N. secretary-general's special representative for West Africa, said in a statement Wednesday that the attack took place near Kontcha, Cameroon.

The contractor's nationality was not released. Three Nigerians and one Cameroonian also were killed in the Tuesday afternoon attack. Several others were wounded.

The U.N. says the group was part of a technical monitoring team carrying out a field mission related to border demarcation.

There are no immediate claims of responsibility, and it is not known which armed group was responsible.

The Nigeria-based Boko Haram Islamic insurgency has spilled across borders into neighboring countries including Cameroon.

AP