An unknown gunman has killed environment minister Emmanuel Niyonkuru in the conflict-ridden East African nation of Burundi, a police spokesperson said today.

The minister was shot dead with a pistol in the early hours of today in the streets of the Rohero neighbourhood in the capital, Bujumbura, police spokesperson Pierre Nkurikiye said on Twitter.

Police arrested a woman over her alleged involvement in the assassination, the spokesperson added.

Burundi has been suffering from ongoing political violence since President Pierre Nkurunziza won a third term in office in July 2015 elections, despite the constitutional two-term limit.

Hundreds of people have been killed by police and armed opposition groups in the violence.

- dpa