Tanzanian President John Pombe Magufuli, 61, has died, the country’s vice president announced, after weeks of uncertainty over his health and whereabouts.

Vice President Samia Suluhu Hassan said in an address on state television on Wednesday that Magufuli died from heart complications at a hospital in Dar es Salaam.

"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.

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.

The Vice President announced a 14-day national mourning period where flags would fly at half-mast.

Magufuli was one of Africa's most prominent coronavirus sceptics, and called for prayers and herbal-infused steam therapy to counter the virus.

Ms. Hassan will be sworn in as the new president and serve the remainder of Magufuli's five-year team which he began last year, according to Tanzania's constitution.

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".

Media reports quoted opposition leader Tundu Lissu last week as saying that Magufuli was being treated for coronavirus in Kenya.

Magufuli declared Tanzania "Covid-19 free" last June and mocked the efficacy of masks, expressed doubts about testing. Coronavirus cases have not been published in the country since May and the government has refused to purchase vaccines.

Police have also reported having arrested four people on Monday for spreading rumors on social media of the president's illness.