Heavily armed assailants have stormed two army posts in Burundi's capital Bujumbura in coordinated attacks.
The attacks in the early hours of Friday sparked clashes with troops that left at least 12 fighters dead, an army spokesman said.
Gaspard Baratuza told state radio that 20 other fighters were arrested after the attacks on a base at Ngagara in the north of Bujumbura and a military training college in the south.
Presidential media adviser Willy Nyamitwe wrote on Twitter: “Sindumuja [a name for armed opponents] tried to attack military camps but they failed,” describing the raids as “a diversion” to try to free prisoners.
“Situation is returning to normal as firearms are seized, many Sindumuja assailants killed or arrested,” he added.
Witnesses said there was heavy firing, including artillery, lasting several hours at the Ngagara base and the ISCAM Higher Institute of Military Training in Musaga.
According to Jean-Claude Karerwa, deputy spokesman of President Pierre Nkurunziza, a cabinet meeting scheduled for Friday would address the unrest.
A source in the presidency said a declaration of a state of emergency was under consideration.
The fighting on Friday was the heaviest in months since conflict broke out following a failed coup in May.
The unrest was mainly sparked by Nkurunziza's bid for a third term, which he later won in disputed elections in July.
Months of street protests have devolved into regular armed attacks with gunfire disrupting the nights and bodies appearing on city streets almost daily.
Attacks on security forces have escalated with frequent ambushes of police convoys by rebels armed with assault rifles and rocket-propelled grenades and mortars aimed at government installations.
