Nigeria's president, Muhammadu Buhari says he's shocked to learn that a military officer and his female partner were shot dead and then beheaded in the south-east of the country.

Mr Buhari has ordered that the perpetrators of the barbaric crime be brought to justice.

The authorities have accused a separatist group, the Indigenous People of Biafra, for killing the couple as they travelled for their wedding last weekend.

The group has denied their involvement.

Gunmen in south-east Nigeria have recently stepped up their attacks mostly targeting the security forces.