Burundi looked set to adopt constitutional reforms that could allow President Pierre Nkurunziza to remain in power until 2034, with official results on Friday showing a "yes" vote winning in 14 of 18 provinces.
The official results, published by a coalition of 15 public and private radio stations which covered Thursday's referendum, showed a majority of "yes" votes in the 14 provinces.
The referendum comes three years after Nkurunziza sought a third term in office, plunging the country into crisis with a crackdown on protests, an attempted coup and spiral into violence leaving 1,200 dead and displacing some 400,000.
Critics say the referendum has struck a death blow to the Arusha peace deal which ended a 1993-2006 civil war, and ushered in measures to ensure power would not be concentrated in either the hands of the majority Hutu or minority Tutsi, after decades of violence between the communities.
In traditional opposition strongholds, where the ruling CNDD-FDD has never won an election, such as the capital Bujumbura and southern Bururi, the "yes" vote won 53.9 percent and 51.97 percent respectively.
This prompted accusations of fraud from opposition parties who complained of massive voter intimidation. Ruling party deputy secretary general Joseph Ntakarutimana denied these "exaggerations".
The other provinces recorded between 61 percent and 84 percent of "yes" votes.
The media coalition reported turnout in the provinces counted stood at over 90 percent. Some 4.8 million people had registered to vote.
Burundi's constitution currently allows presidents to seek two five-year mandates. Nkurunziza circumvented that in 2015 by claiming he had been elected by parliament in 2005.
The new constitution will increase term lengths to seven years, which would allow Nkurunziza to start again from scratch in 2020.
If passed, Nkurunziza would be the latest in a long line of African leaders to tweak the constitution in order to stay in power, along with Rwanda's Paul Kagame, Uganda's Yoweri Museveni, Cameroon's Paul Biya and others.
Other changes weaken constitutional constraints over the feared national intelligence agency and allow the revision of ethnic quotas seen as crucial to peace after the war.
The new constitution also gets rid of one of two vice-presidents and shifts powers from the government to the president.
"There were articles preventing authorities from doing good, paralysing government works. These reforms will allow us to move things forward," said Ntakarutimana.
The opposition and rights groups have said that, much like the preceding three years, the run-up to the referendum was marked by threats, intimidation and violence.
There were "intimidations of every kind and even people going to polling stations, forcing people to vote against their will," said main opposition leader and former rebel Agathon Rwasa.
Human Rights Watch said Friday it had documented "15 killings, six rapes used as punishment against those seen as against the (ruling) CNDD-FDD, eight abductions, and numerous other violations."
The watchdog said that with fear preventing the report of abuses, the real figures were likely much higher.