Rwanda's president has accused Burundi's leaders of killing their own people as human rights activists accuse security forces of killing 11 people over the weekend.
Paul Kagame's comments could cause tensions between the neighbouring countries to rise.
He made them after Burundi's president, Pierre Nkurunziza, repeatedly accused Rwanda of precipitating violence and instability in Burundi.
"Are these leaders or what, who kill their own people from morning to evening, dump them on the street and in streams, and then stand up and start accusing Rwanda?" Kagame said in a speech that was released on Sunday.
Activists said that about 200 people have been killed in Burundi since April, when Nkurunziza announced his intention to seek a third term, which his critics said was unconstitutional.
Nkurunziza, however, went on to win an election that was boycotted by the opposition in July.