Rwanda on Sunday dismissed a Burundi assertion that it armed a rebel group accused of grenade explosions that wounded dozens, heightening strained relations between the East African neighbors.
At least 38 people were injured in the attack on Friday in Bujumbura, Burundi's interior ministry said, laying the blame on the RED-Tabara rebels.
Gitega said Kigali provided training and logistical support to the rebels, who have been fighting Burundi's government from bases in the Democratic Republic of Congo.
Rwandan government spokesperson Yolande Makolo rejected the allegations, saying they "have absolutely no connection" with the attack.
"Burundi has a problem with Rwanda, but we have no problem with Burundi," her office said in a statement.
"We call on Burundi to solve its own internal problems and not associate Rwanda with such despicable matters."
Relations between the two countries have often been tempestuous and Rwanda has previously denied claims it backs the rebels.
RED-Tabara, who emerged in 2011, is accused of waging deadly violence in Burundi since 2015 but had not been active there since September 2021, when it carried out several attacks, including on the airport in Bujumbura.
On Sunday, the group denied it was involved in the attack on Friday.
"These hasty statements each time, without any investigation, question the responsibility of the CNDD-FDD regime in crimes," it said in a statement, referring to the ruling party.
"The government should tackle the fundamental problems haunting the people instead of engaging in a diversionary exercise."
RED-Tabara is the most active of Burundi's rebel forces with an estimated 500 to 800 fighters.
In January, Burundi accused Rwanda of supporting the group and closed the border. Two weeks earlier, there had been an attack that killed 20 which Burundi said was carried out by RED-Tabara.
The border remained closed between 2015 and 2022 amid mutual claims of supporting rebel groups.