At least nine gunmen in Burundi were shot dead in clashes with security forces in recent days, officials said Wednesday, with a new rebel group claiming nine soldiers were killed.

"Unidentified gunmen entered the town of Buganda, then went into Murwi from neighbouring Democratic Republic of Congo since Monday," Anselm Nsabimana, governor of Burundi's northwestern Cibitoke region, told reporters.

"At least nine attackers were killed," he said, adding that several firearms including rocket propelled grenades were seized, but that "no soldier or civilian were killed or injured."

However, a member of the previously unknown group -- calling themselves the Murundi People's Front, 'the Saviours' (FPM-Abatabazi) -- said that nine soldiers had been killed.

"On Monday we started the armed struggle to liberate the people of Burundi from the yoke imposed by (President) Pierre Nkurunziza," Ntwari Israel, the rebel's deputy commander told AFP by telephone.

"The governor's statement is false," he said, claiming over 17 soldiers were also wounded, with "minimal loss" to the rebels.

Officials said calm had returned to the area.

"This group was dealt with, as will any other group that will try to attack Burundi from a neighbouring country," Nsabimana said.

Since the 2010 boycott of the general elections by Burundi's opposition, several acts of violence claimed by a number of rebel groups have rocked the small central African nation.

In 2011, groups labelled "armed bandits" by the government launched several attacks, prompting a crackdown by Bujumbura.

Rights groups as well as the UN Security Council have voiced concern over a series of "extra-judicial killings" in the country since 2010.

Observers have feared that Burundi could slide back into full-blown civil conflict, which ended in a 2006 ceasefire agreement after 13 years of civil war.