A senior Burundi army officer and ally of the president was shot dead in the Defence Ministry compound on Tuesday, the army and soldiers said, the latest in a series of killings in an almost year-long crisis that risks plunging the nation back into war.
Lieutenant Colonel Darius Ikurakure was shot by an assassin dressed in a military uniform, the army said in a statement. Other soldiers earlier gave a similar account and also said he was shot while inside the ministry compound.
Tit-for-tat killings of pro-government and opposition figures have prompted international concerns that Burundi, which emerged from an ethnically charged civil war a decade ago, could slide back into conflict.
The crisis has rattled a region with a history of ethnic fighting, including neighbouring Rwanda which suffered a genocide in 1994.
"After the crime, the criminal managed to escape," army spokesman major Clément Cimana said in a statement, adding the weapon had been recovered and the authorities were still seeking to track down the attacker. He called for unity in the army.
U.N. Secretary-General Ban Ki-moon condemned the killing.
"Such acts of violence risk exacerbating the current crisis in Burundi," Ban's spokesman Farhan Haq told reporters. "The secretary-general reiterates his appeal for Burundians to resolve their differences peacefully and to engage immediately in an inclusive and transparent political dialogue."
Soldiers said the assassin had attacked just after midday, when people may have been away at lunch, allowing him to flee.
Ikurakure was commander of a combat engineering battalion based in Muzinda, northeast of the capital, Bujumbura. He was seen as close to Nkurunziza, with whom he fought as a rebel during the civil war that ended in 2005.
Opponents accused him of being behind arbitrary arrests and killings in some areas of Bujumbura over the past year.
The government says it only arrests those behind violence, and dismisses accusations of extra-judicial killing.
Burundi's crisis erupted in April when President Pierre Nkurunziza said he was bidding for a third presidential term. His opponents said the move was unconstitutional but he went on to win a disputed election three months later.