Tanzania's President John Magufuli has died aged 61, the country's vice-president has announced.
He died on Wednesday from heart complications at a hospital in Dar es Salaam, Samia Suluhu Hassan said in an address on state television.
Magufuli, a divisive leader who won a second term in October in an election tainted by violence and allegations of fraud, had not been seen in public since 27 February. This led many to believe that he was sick and possibly incapacitated. He had a history of heart problems and wore a pacemaker.
Government officials had insisted Magufuli was working normally and that citizens should ignore “hateful” rumours coming from abroad.
Police arrested four people last week on charges of spreading false information about the health of political leaders.
Opposition politicians said last week that he had contracted Covid-19, but this has not been confirmed.
Mr Magufuli was one of Africa's most prominent coronavirus sceptics, and called for prayers and herbal-infused steam therapy to counter the virus.
He also mocked the efficacy of masks, expressed doubts about testing, and teased neighbouring countries which imposed health measures to curb the virus.
According to Tanzania's constitution, Ms Hassan will be sworn in as the new president within 24 hours and should serve the remainder of Mr Magufuli's five-year term which he began last year.
The US state department spokesperson, Ned Price, said the US remained committed to continuing to support Tanzanians as they advocated for respect for human rights and fundamental freedoms and worked to combat the pandemic.
Magufuli denied the local spread of Covid-19 in the country, discouraged the mention of the disease by health workers, and claimed without evidence that vaccines were dangerous, suggesting instead that people pray and inhale herb-infused steam.
Despite repeated requests by the World Health Organization, Tanzania has not published any statistics on cases since May, when it registered 509 infections. It has no known testing programme in place and health officials have been forbidden from mentioning the virus.
Evidence suggests Tanzania was hit hard by a recent surge of infections across southern and parts of eastern Africa brought on by the spread of the new South African variant.
The extent of any outbreak in Tanzania is unclear, but South Africa, which has roughly the same population, has suffered almost 50,000 deaths from Covid-19, according to official statistics, and many more according to excess mortality figures.