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 had not been seen in public for more than two weeks, and rumours have been circulating about his health.
Opposition politicians said last week that he had contracted Covid-19, but this has not been confirmed.
Magufuli was one of Africa's most prominent coronavirus sceptics, and called for prayers and herbal-infused steam therapy to counter the virus.
"It is with deep regret that I inform you that today... we lost our brave leader, the president of the Republic of Tanzania, John Pombe Magufuli," Vice-President Hassan said in the announcement.
She said there would be 14 days of national mourning and flags would fly at half mast.
According to Tanzania's constitution, Ms Hassan will be sworn in as the new president and should serve the remainder of Magufuli's five-year team which he began last year.
Magufuli was last seen in public on 27 February, but Prime Minister Kassim Majaliwa insisted last week that the president was "healthy and working hard".
He blamed the rumours of the president's ill-health on "hateful" Tanzanians living abroad.
But opposition leader Tundu Lissu told the BBC that his sources had told him Magufuli was being treated in hospital for coronavirus in Kenya.
Magufuli declared Tanzania "Covid-19 free" last June. He mocked the efficacy of masks, expressed doubts about testing, and teased neighbouring countries which imposed health measures to curb the virus.
Tanzania has not published details of its coronavirus cases since May, and the government has refused to purchase vaccines.
On Monday, police said they had arrested four people on suspicion of spreading rumours on social media that the president was ill.
"To spread rumours that he's sick smacks of hate," Mr Majaliwa said at the time.
Tanzania’s economy grew around 7.1 per cent last year, beating the government’s own revised forecast, Prime Minister Kassim Majaliwa said.
In November, the country trimmed its gross domestic product (GDP) to 7.0 per cent from 7.1 per cent. That forecast had also been revised from 7.4 per cent. But Majaliwa said East Africa’s third-largest economy grew faster than expected last year owing to an increase in mining activity.
“Latest data ... shows that the country’s gross domestic product grew 7.1 per cent in the period between January and December 2017, compared to a GDP growth of 7.0 per cent in 2016,” Majaliwa said in the parliamentary presentation obtained by Reuters.
The session on Monday was held behind closed doors.
Full-year GDP growth in 2017 was driven by mining and quarrying (17.5 per cent), transport and storage (16.6 per cent) and construction (14.7 per cent) activities, he said.
The World Bank cut its forecast for Tanzania’s full-year GDP growth in November to 6.6 per cent due to slowdowns in public spending and growth of credit to the private sector. Tanzania has pledged to boost public investment in infrastructure projects, including a standard gauge railway, new roads and an expansion of ports.
But some investors have been unnerved by some policies from the government of President John Magufuli, who is nicknamed “The Bulldozer” for his governing style.
“There appears to have been an overall deterioration in business sentiment due to the perceived risks resulting from the unpredictability of policy actions,” the World Bank said in its economic update on Tanzania in November.