The body's Regional Director for Africa Matshidiso Moeti says there are concerns about the rise of cases reported in the East African country in the last few days.

"Certainly in Tanzania we have observed that physical distancing, including the prohibition of mass gatherings, took some time to happen and we believe that these might have been probable factors that led to a rapid increase in cases there," Dr Moeti said at a briefing.

Tanzania's President John Magufuli has been widely criticised for encouraging the public to continue gathering in places of worship, rather than imposing stringent restrictions to mitigate the spread of the coronavirus outbreak.

Tanzania reported its first case on 16 March and by Thursday 284 people had tested positive for coronavirus.

The government at the time closed all schools and universities for an initial period of 30 days to prevent further spread of the virus. The closure was extended last week.

The president has ruled out a lockdown in the commercial capital, Dar es Salaam, where most of the positive cases are citing the economy.