Burundi on Monday accused the country's main rebel group of attacking a bereaved family and killing nine people including a soldier, while the RED-Tabara insurgents said they had killed six troops.
The attack late on Sunday in the western region of Buringa, just north of the economic capital Bujumbura, borders the Democratic Republic of Congo, where the RED-Tabara group has rear bases.
"Terrorists from the RED-Tabara group, armed with guns, attacked a family in mourning," a statement from the presidency said.
It said nine people, including six women and a soldier, were killed in the "cowardly attack" and five people were wounded.
The presidency said the rebels also ransacked an office of the ruling CNDD-FDD party and accused Rwanda of backing the rebels.
The group is the most active of all the rebel outfits in Burundi and is estimated to have between 500 and 800 fighters.
RED-Tabara claimed the attack on X, formerly Twitter, and said its forces had "killed six soldiers, destroyed the CNDD-FDD office and seized arms and ammunition".
It also posted a photograph of a destroyed building painted in the colours of the ruling party.
A security source told AFP, on condition of anonymity, that the rebels had killed 10 civilians, five soldiers and flattened the ruling party office using rocket launchers.
Burundi had accused the RED-Tabara group of carrying out an attack on December 22 near the border with DRC and killing 20 people, including women and children.
RED-Tabara claimed responsibility in a message on X, saying it targeted a border post and killed nine military personnel and a policeman.
In another post on X, it denied it killed any civilians and said the group "is not supported by any country. It only has the support of the Burundian people".
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.
Burundi has closed its border with Rwanda and President Evariste Ndayishimiye has accused Rwanda of backing the rebels -- a claim denied by Kigali.