At least 38 people were injured in the attack, Pierre Nkurikiye, the spokesperson for Burundi's interior ministry said.

"These terrorists were recruited, trained and even equipped with weapons in Rwanda and by Rwanda," Mr Nkurikiye added.

Rwanda's government dismissed the allegations on Sunday, saying Rwanda "has absolutely no connection" with the attack and had "no reason to be involved" in it.

"We call on Burundi to solve its own internal problems and not associate Rwanda with such despicable matters," the statement by the office of the government spokesperson added.

Red Tabara, the group accused of executing the grenade attack, has also denied responsibility, saying it "does not attack innocent civilians".

Relations between Rwanda and neighbouring Burundi and Democratic Republic of Congo have become strained in recent years, with both neighbours accusing Rwanda of funding rebel attacks in their countries.

Rwanda has repeatedly denied these allegations.