BUJUMBURA, Burundi — Burundi's president joined long lines of voters Thursday in a referendum that could extend his rule until 2034, despite widespread opposition and fears that the country's years of deadly political turmoil will continue.
"I thank all Burundians who woke up early in the morning to do this noble patriotic gesture," President Pierre Nkurunziza said after casting his ballot in his home province of Ngonzi.
Nkurunziza had campaigned forcefully for the constitutional changes that include extending the president's term from five years to seven. That could give him another 14 years in power when his current term expires in 2020.
He is the latest in a number of African leaders who are changing their countries' constitutions or using other means to stay in office.
Nkurunziza's opponents say he already has ruled longer than the constitution allows. More than 1,200 people have been killed in protests in this East African nation since he decided in April 2015 to pursue a disputed third term.
Observers in recent days have expressed alarm at reported violence and intimidation of the referendum's perceived opponents, including threats of drowning and castration.
A presidential decree criminalized calls to abstain from voting Thursday, with a penalty of up to three years in jail.
Bujumbura, the capital, had long lines of voters as security forces were deployed across the city. Five million people across the country had been registered to vote.
"I just came because I am told those who won't vote will be punished," one teacher said while waiting to vote in the capital, speaking on condition of anonymity out of fear for her safety.
While voting appeared to go smoothly in most areas, activist group iBurundi reported alleged intimidation. In the central province of Karuzi police "arbitrarily arrested" a representative of opposition group Amizero y'Abarundi who was there to observe the voting, iBurundi told The Associated Press.
Nkurunziza's main opponent, Agathon Rwasa of Amizero y'Abarundi, condemned what he called irregularities in the vote.
"Intimidations of all sorts are happening. There are some people who are going even to the voting booth to tell people how they must vote. This is contrary to the ethics of democracy and its spirit," Rwasa told reporters after voting.
The government was not immediately available to respond to the allegations. The government strongly denies that it targets its own people, calling such charges malicious propaganda spread by exiles.
Authorities ahead of the referendum imposed temporary broadcasting bans on the BBC and Voice of America, citing alleged violations.
It was not clear when final results of Thursday's vote would be announced.
"We never anticipated much drama today as nobody would dare to protest the vote in this environment," Lewis Mudge, a researcher with Human Rights Watch, said in an email. "Our real worry in the coming days, weeks and months is that people who were opposed to the referendum could be punished."
Tensions rose last week after unidentified attackers with machetes and guns carried out a massacre Friday in the rural northwest near Congo, killing 26 people, many of them children. The government blamed a "terrorist group." It is not clear whether the attack was related to Thursday's vote.
The 54-year-old Nkurunziza, a former rebel leader, rose to power in 2005 following a peace deal ending a civil war in which some 300,000 people died. He was re-elected unopposed in 2010 after the opposition boycotted the vote.
Nkurunziza in 2015 said he was eligible for a third term because lawmakers, not the general population, had chosen him for his first term. Critics called a third term unconstitutional as the deal ending the civil war says the president can be re-elected only once, but the constitutional court said Nkurunziza could run again.
Hundreds of thousands of people fled the political violence that followed Nkurunziza's decision, sheltering in neighboring countries. International Criminal Court judges last year authorized an investigation into allegations of state-sponsored crimes.
Observers expressed concern that changing the constitution to extend Nkurunziza's time in office would only ignite more trouble in a country with a long history of ethnic tensions.
The changes "could start to dismantle the carefully negotiated Hutu-Tutsi balance," according to the International Crisis Group, which warned that "the regime's repression, the potential demise of power-sharing in Burundian institutions and the crumbling economy are harbingers of instability."