The head of an opposition party in Burundi says their spokesman was killed overnight in the capital, Bujumbura.

Chauvineau Mugwengezo of the opposition UPD Zigamibanga said Tuesday that party spokesman Patrice Gahungu was shot and killed by unknown gunmen on Monday evening outside his home.

In May Zedi Feruzi, the then leader of UPD Zigamibanga, was assassinated in Bujumbura amid violent street protests against President Pierre Nkurunziza's bid for a third term in office.

Nkurunziza won re-election in July polls widely seen as not credible, but violence persists in Bujumbura.

In August a top military general who once led the intelligence services, Adolphe Nshimirimana, was killed in a drive-by shooting in Bujumbura, sparking concerns of revenge killings in which regime loyalists and opponents target each other.