Three Burundi army officers have been arrested for suspected involvement in a failed bid to assassinate a top advisor to the president, according to police and security sources.

The attack took place late on Monday when a group of gunmen ambushed Willy Nyamitwe, the government's top spokesman, as he was returning to his home in the capital Bujumbura.

"It's terrorism," Burundi police spokesman Pierre Nkurikiye tweeted late Friday.

Security sources

"Two colonels and a captain were arrested yesterday (Thursday) over the attempt on the life of Willy Nyamitwe."

Security sources named the three as Captain Celestin Iranyibutse and colonels Nestor Bahati and Jean-Baptiste Miruho, known as Miros.

Burundi police had already arrested a lieutenant-colonel and a corporal on Monday, hours before the assassination attempt.

Opened fire

The assailants who attempted to kill Mr Nyamitwe, the most public face of the government, opened fire and threw grenades on Monday, killing one of his bodyguards, but leaving the senior spokesman with only minor injuries to his arm.

The three officers arrested after the attack are being investigated "for attempted assassination and an attack on the internal security of the state... for their participation in the assassination attempt against Willy Nyamitwe and their links with armed groups seeking to destabilise Burundi," a senior army source told AFP.

Rebel ranks

The source added that the suspects are former members of the former Hutu rebel group that fought against the formerly Tutsi minority-dominated army during the Burundian civil war.

The current ruling CNDD-FDD party was formed from the Hutu rebel ranks.

The government has made little comment on the assassination bid.