Rwanda's government has denied accusations that it armed a rebel group alleged to have carried out a grenade attack in Burundi's economic hub, Bujumbura.
At least 38 people were injured in Friday's 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 it "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," a government statement said.
Red Tabara, the group accused of executing the grenade attack, has also denied responsibility, saying it "does not attack innocent civilians".
Rwanda's relationships with neighbouring nations Burundi and the Democratic Republic of Congo have become strained in recent years.
Both neighbours have accused Rwanda of funding rebel attacks in their countries, but Rwanda has repeatedly denied these allegations.