In a statement on Monday, he described the incident in the conflict-hit North-West region as a heinous act committed by "cowardly criminals".

"I convey my sincere condolences to the family of Cherish Limnuyu, a 15-year-old student of GHS Nwangri," Mr Biya said on X, adding that: "I equally wish a speedy recovery to the injured".

Students were celebrating Youth Day when an improvised explosive device planted by separatist fighters went off near a ceremonial square.

The separatists had ordered a "ghost town" stayaway strike and wanted to block the government-organised youth event from going ahead.

Three suspects have been arrested, according to the regional governor. A church service has been held at the site of the explosion in support of the victims.

On Monday, elderly women in Nkambe marched barefoot with peace plants in hand, denouncing Sunday’s attack. This town has enjoyed relative calm over the years, with education and other activities going on with little disruption from the separatists.

But this attack has further reinforced concerns about the volatile security context in the two Anglophone regions of Cameroon.