NAIROBI, Kenya — President John Magufuli of Tanzania, a populist leader who played down the seriousness of the coronavirus pandemic and steered his country away from democratic ideals, died on Wednesday in the port city of Dar es Salaam. He was 61.
Vice President Samia Suluhu Hassan said in a brief televised address that Mr. Magufuli had died of heart complications while being treated at Mzena Hospital. The announcement followed more than a week of intense speculation that Mr. Magufuli was critically ill with Covid-19 — reports that senior government officials had repeatedly denied.
Ms. Hassan did not specify Mr. Magufuli’s underlying illness but said that he had suffered from chronic atrial fibrillation for more than a decade. She announced 14 days of national mourning and said that flags would fly at half-staff nationwide.
According to the Tanzanian Constitution, Ms. Hassan will be sworn in as president to serve the remainder of the five-year term that Mr. Magufuli began when he won re-election last October. The move will make her Tanzania’s first female leader.
Mr. Magufuli, a trained chemist, was first elected in October 2015 on an anticorruption platform. He was initially lauded for his efforts to bolster the economy, stem wasteful spending and upgrade Tanzania’s infrastructure.
But the leader, popularly known as “the Bulldozer,” was soon accused of muzzling dissent, rolling back freedom of expression and association, and pushing through laws that shored up his Party of the Revolution’s grip on power.
That marked a sharp departure from policies of his two immediate predecessors, who had promoted their East African nation as a peaceful, business-friendly democracy.
During his first term, Mr. Magufuli’s government banned opposition rallies, revoked the licenses of nongovernmental organizations and introduced laws that critics said repressed independent reporting. He also said that pregnant girls should not be allowed in school.
Rights groups accused his government of failing to carry out credible investigations into the killings, abductions and persecution of journalists who were critical of the government and opposition figures.
As Mr. Magufuli sought a second term last fall, the authorities made it harder for opposition parties to campaign, froze the bank accounts of civil society groups, denied accreditation to election observers and journalists, and refused to let opposition representatives into polling stations.
On voting day, at least 10 people were killed when violence broke out in the semiautonomous archipelago of Zanzibar after citizens said they had seen soldiers delivering marked ballots.
Mr. Magufuli won that election with 84 percent of the vote amid accusations of widespread fraud and irregularities. Tundu Lissu, the main opposition candidate running against him, was accused of trying to overthrow the government and had to leave the country. He remains in exile in Belgium.
Over the past year, Mr. Magufuli came under intense criticism at home and abroad for his handling of the coronavirus pandemic. He railed against masks and social distancing, promoted unproven remedies as cures and said that God had helped the country eliminate the virus.
Tanzania has not shared data on the coronavirus with the World Health Organization since April, and it has reported just 509 cases and 21 deaths, figures that have been widely viewed with skepticism.
As vaccine rollouts began worldwide, Mr. Magufuli discouraged the Health Ministry from securing doses for Tanzania.
“Vaccines don’t work,” he claimed in a speech to a maskless crowd in late January. “If the white man was able to come up with vaccinations, then vaccines for AIDS would have been brought. Vaccines for tuberculosis would have made it a thing of the past. Vaccines for malaria would have been found. Vaccines for cancer would have been found.”
Such statements drew condemnation from the World Health Organization as well as the Roman Catholic Church in Tanzania. Dr. Matshidiso Moeti, the W.H.O. regional director for Africa, urged the Tanzanian government to prepare the infrastructure to distribute the doses, writing on Twitter, “Science shows that #VaccinesWork.”
In February, the United States Embassy in Tanzania warned of “a significant increase in the number of Covid-19 cases” and said that “limited hospital capacity throughout Tanzania could result in life-threatening delays for emergency medical care.”
Mr. Magufuli’s death came just days after speculation that he was sick with the virus. The rumors started swirling after Mr. Lissu, the opposition figure in exile, said that the president had Covid-19 and was being treated in a hospital in neighboring Kenya.
Mr. Lissu urged the authorities to disclose the whereabouts of the president, who had not been seen in public for almost two weeks. Mr. Magufuli did not attend a virtual summit for leaders of the East African regional bloc on Feb. 27.
Tanzanian officials had dismissed the speculation and said that Mr. Magufuli was working as usual.
After Mr. Magufuli’s death was announced on Wednesday, the leader of opposition party Act Wazalendo called on Tanzanians to show “patience and understanding” as the country undergoes a critical transitional period.
“This is an unprecedented moment,” the opposition party leader, Zitto Kabwe, said in a statement, “one that will undoubtedly move us all in very personal ways.”
John Pombe Joseph Magufuli was born on Oct. 29, 1959, in the district of Chato in what is now northwestern Tanzania and was then known as Tanganyika. He earned a bachelor’s degree in education from the University of Dar es Salaam and, in 2009, a doctorate in chemistry from the same university, according to the presidential office’s website.
Before becoming president, he was a member of Tanzania’s Parliament and held a number of cabinet posts. He developed a reputation for fighting corruption while working in cabinet positions, including as the minister of lands, fisheries and public works.
Mr. Magufuli is survived by his wife, Janet, a primary-school teacher; and two children.