Burundi has closed its borders with Rwanda after accusing its neighbour of funding rebel attacks.
Last December Red Tabara, a Burundian rebel group, killed 20 people near the border with the Democratic Republic of Congo.
Rwandan President Paul Kagame denies the charge, but Burundi's government has branded him a "bad neighbour".
"We have stopped ties with him until he changes," said Burundi's Interior Minister Martin Niteretse.
Burundian President Évariste Ndayishimiye made the accusation in December following the attack.
The Rwandan government responded that it "regrets the unilateral closure of the border by Burundi", according to AFP.
It said the border closure was an "unfortunate decision" which violated the principles of regional cooperation and the integration of the East Africa Community.
Red Tabara admitted to carrying out the December attack, but said they had only killed nine soldiers and one police officer.
The group operates from DR Congo's South Kivu province bordering Burundi.
It was not immediately clear whether the border closure included both land and air.
In 2015 Burundi closed its border to Rwanda due to political tensions and then because of Covid-19. Seven years later the borders reopened.
During that time land crossings were not permitted. But the airline carrier RwandAir never stopped its commercial flights to Burundi.
Relations between Rwanda and Burundi have been tenuous despite their having a similar language, ethnic composition and colonial history.
