The referendum comes as Burundi remains mired in a deep political crisis, triggered by Nkurunziza's run for a controversial third term in 2015, that has killed 1 200 and forced 400 000 from their homes. Voting in Thursday's straight yes or no ballot is due to begin at 06:00 with polls closing at 16:00.

At least 4.8 million people, or a little under half the population, have signed up to vote, according to the Independent National Electoral Commission (CENI), which is running the referendum. 

The changes will be adopted if more than 50% of cast ballots are in favour. But with opponents cowed, beaten, killed or living in exile, there seems little doubt the amendments will pass, enabling the 54-year-old who has been in power since 2005, to remain in charge for another 16 years.

Exiled civil rights activists this week called for sanctions against Nkurunziza's regime. The vote is taking place in tightly-controlled conditions, and a presidential decree ruled earlier this month that anyone advising voters to boycott the vote risks up to three years in jail.

The tiny central African nation has struggled to recover from a brutal and destructive civil war from 1993-2006 that left more than 300 000 people dead.

--AFP--