The head of the World Health Organization on Sunday appealed to Tanzania to take "robust action" to combat Covid-19 in the country, where the president has long played down the virus.
President John Magufuli has claimed coronavirus has been has fended off by prayer in Tanzania, and refused to take measures to curb its spread.
But a recent spate of deaths attributed to pneumonia has struck both members of the public and government officials.
And Magufuli on Friday appeared to admit the coronavirus was circulating in his country after months of denial.
WHO director general Tedros Adhanom Ghebreyesus said a number of Tanzanians travelling to neighbouring countries and beyond have tested positive for the coronavirus.
"This underscores the need for Tanzania to take robust action both to safeguard their own people and protect populations in these countries and beyond," he said in a statement.
Tedros said he had urged Tanzania in late January to take measures against the pandemic and to prepare for vaccinations.
"Since then I have spoken with several authorities in Tanzania but WHO is yet to receive any information regarding what measures Tanzania is taking to respond to the pandemic.
- Papaya, quail and goat -
"This situation remains very concerning. I renew my call for Tanzania to start reporting COVID-19 cases and share data.
"I also call on Tanzania to implement the public health measures that we know work in breaking the chains of transmission, and to prepare for vaccination."
The country last gave case figures in April 2020, reporting 509 infections.
At the same time Magufuli revealed he had secretly had a variety of items tested for the virus -- of which a papaya, a quail and a goat apparently tested positive.
On Wednesday, the vice president of semi-autonomous Zanzibar, Seif Sharif Hamad, died after his opposition party admitted he had contracted coronavirus.
The head of the civil service, John Kijazi, also died Wednesday.
The cause of death has not been revealed. But Magufuli brought up Covid-19 at his funeral.
"When this respiratory disease erupted last year, we won because we put God first and took other measures. I'm sure we will win again if we do so this time around," he said.
However dissent is mounting within the country to the government's position on the pandemic.
On Saturday, the Tanzania Law Society became the first professional body to call on the government to openly recognise the virus and take adequate measures.