Burundi said on Thursday it had closed the border with Rwanda, nearly two weeks after accusing its neighbour of supporting rebels who carried out attacks on its soil.
Burundi says the RED-Tabara group staged an attack on December 22 near the border with the Democratic Republic of Congo (DRC), killing 20 people, including women and children.
President Evariste Ndayishimiye has since accused Rwanda of backing the rebels -- a claim denied by the Rwandan government.
"We have closed our borders (with Rwanda), anyone who tries to go there will not get through. The decision has been made," Burundi's Interior Minister Martin Niteretse told reporters on Thursday.
"After having noted that we had a bad neighbour, (Rwandan President) Paul Kagame... we stopped all relations with him until he returns to better feelings," the minister added.
He said Rwanda "shelters criminals who harm Burundians".
Relations between Burundi and Rwanda have often been tempestuous.
Although ties began improving after Ndayishimiye took power in 2020, they have soured again over Burundi's involvement in the DRC.
RED-Tabara is accused of waging deadly violence in the East African country since 2015 but had not been active there since September 2021, when it carried out several attacks, including on the airport in the main city of Bujumbura.