Tanzania's leadership faced calls for a smooth succession on Thursday after president John Magufuli, Africa's most vehement coronavirus sceptic, died following an 18-day absence from public life that drew speculation about his health.

An opposition leader urged the immediate swearing in of Vice President Samia Suluhu Hassan as successor, saying that would avoid a constitutional vacuum and prevent uncertainty.

But by 1400 local time (1100 GMT), more than 15 hours after Hassan announced Magufuli's death in an address to the nation, there was no official word on plans for her swearing in.

The ruling CCM party called for calm and said there would be a special meeting of its central committee on Saturday.

Magufuli's death, the first of a Tanzanian leader while in office, opens the prospect that the country will gain its first female president.

The constitution says Hassan, 61, should assume the presidency for the remainder of the five-year term that Magufuli began serving last year after winning a second term.

Speaking on state television late on Wednesday, Hassan said Magufuli, 61, had died from the heart disease that had plagued him for a decade. She said burial arrangements were under way but did not indicate when she would be sworn in.

Government spokesperson Hassan Abbasi did not respond to calls and texts seeking comment on succession plans.

Magufuli had not been seen in public since February 27, sparking rumours he had Covid-19. On March 12, officials denied he had fallen ill and on Monday Hassan had urged Tanzanians not to listen to rumours from outside the country.

As late as Wednesday, she sent 'greetings' from Magufuli in a remarks to an audience in the coastal region of Tanga.

"The VP has to be sworn in immediately," opposition leader Zitto Kabwe told Reuters by phone from Dar es Salaam. "The constitution doesn't allow a vacuum ... I will be concerned if the day passes without her being sworn in."

A source who advises businesses operating in Tanzania said “The next 48 hours are crucial ... There is likely to be uncertainty. Some people will want to purge some Magufuli hardliners, but given how he restructured the intelligence services, that is easier said than done.”

OPPOSITION

Nicknamed "The Bulldozer" because of his reputation for pushing through policies despite opposition, Magufuli drew international criticism for his unorthodox and increasingly authoritarian tactics.

Citing Magufuli's opposition to foreign interference and focus on social development, China on Thursday expressed its condolences over his death, state news agency Xinhua reported.

Thabit Jacob, a Tanzanian scholar at the Roskilde University in Denmark, said there appeared to be a consensus between top political and security figures whom he speaks to about the need for a smooth transition that followed the constitution.

Although Hassan publicly championed Magufuli's leadership style and frequently represented him abroad, she has been more soft spoken and less confrontational than the president.

“The vice president hasn’t given the impression of significant popularity or influence within the (ruling party)," said Fergus Kell, Africa analyst at the Chatham House think-tank in London. "This could throw up some potential challenges in terms of managing competing interests and generating the required support within the ruling party to govern effectively.”

Magufuli was a vocal Covid-19 sceptic who urged Tanzanians to shun mask-wearing and denounced vaccines as a Western conspiracy, frustrating the World Health Organization.

Some people stood on street corners in the downtown area reading newspapers including a headline blaring "Grief" and wept. As has been the case throughout the pandemic in Tanzania, many people were not wearing face masks.