South Africa has more than half of all Covid-19 cases, while Tanzania's lack of data is a "concern".Read more
The director of Africa Centre for Disease Control has expressed concern about Tanzania's handling of the coronavirus pandemic.
Dr John Nkengasong told BBC's Newsday that there was no enough data to determine the situation in Tanzania.
He said the centre had developed a continental joint response strategy to be able to defeat the virus.
"We continue to hope and plead that Tanzania could come forth and report the situation as it is so that we can work collaboratively to stem this virus out of the continent," he said.
He emphasised on the need for all African countries to work together.
"We continue to reach out [to Tanzania] but we are not having the response that we expect," he said.
Tanzania's President John Magufuli has insisted that his country has been "saved" from the virus and declared the country virus free.
The country is getting ready for October elections and is an electioneering mood. People have been going about their business with no masks or social distancing.
BBC News, Dar es Salaam
A small-scale miner in Tanzania, who became an instant millionaire after selling three rough Tanzanite stones for $5.4m (£4.1m), has told the BBC he is optimistic that he will make other big finds of the rare gems in the near future.
Saniniu Laizer - who has been in the mining business in northern Tanzania for more than 15 years - said this was the first time he had struck such luck.
He sold two stones to the government in June for $3.4m, and a third on Monday for $2m.
Mr Laizer said he was confident of discovering more of the precious stones - found only in northern Tanzania - because of analysis conducted by his geologist.
Some have envied Mr Laizer, while others have been inspired by him.
He warned that the business was not as easy as people think.
"It is very expensive to operate the mines. Most of the times we get loans, while at other times we are forced to contribute money among ourselves as small-scale miners," he told the BBC.
Mr Laizer has diversified his business interests and has ventured into other areas, including the construction of shopping malls.
He has also used part of his fortune to build a school and a church in his community.
"Farmers’ and pastoralists’ kids are often not attending school because schools sometimes are very far and children spend most of the time looking after animals," he said.
Business correspondent, BBC News
Uganda is clamping down on informal cross border trade with Tanzania and the unregulated movement of people between the countries, to prevent the spread of coronavirus, in a region where cases of infection have increased.
People living in the Rakai District of Uganda and Missenyi in Tanzania tend to ignore border regulations because they live as one community, with families having relatives on both sides.
Cross border trade and travel is centred on the town of Mutukula, but people also use unregulated roads, which makes the movement of goods and people between both countries hard to monitor.
Some 20 people have recently tested positive for Covid-19 in the region on the Uganda side, after returning from Tanzania.
Now, in order to ensure trade continues, while limiting new cases of infection, the authorities in Uganda's Rakai district have banned cross border travel, unless it is for business.
The clamp down is being enforced by the Ugandan army, with soldiers ensuring residents in the region comply with the directive.
It could raise tensions between the two East African nations and it is not clear how Tanzania will respond.
This week it banned flights from Kenya, after the government in Nairobi deemed measures taken by its neighbour to cope with the pandemic were insufficient.
BBC News, Dar es Salaam
Prominent Tanzanian opposition figure Tundu Lissu has been nominated to run for the presidency in October's general elections by his Chadema party.
He fled the country after narrowly surviving an assassination attempt in the capital, Dodoma, in September 2017. He survived the attack with life-changing injuries after receiving treatment in Belgium and returned last week.
He will now challenge incumbent President John Magufuli.
The nomination was a test for Mr Lissu who had to prove to opponents that he's still a force to be reckoned with. He got 405 votes out of 442 cast by members of the party's national council.
His closest challenger, former Tourism Minister Lazaro Nyalandu, got 36 votes.
Mr Lissu has been a fierce critic of President Magufuli over the last four years.
He seems to have now marshalled support, which many describe as a hurricane, towards the 28 October elections. But questions linger about whether it will be enough to unseat the ruling Chama Cha Mapinduzi (CCM) which has dominated Tanzania's politics since independence.
Mr Lissu's nomination will be approved by the party's national congress on Tuesday.
A Tanzanian miner who made headlines in June for discovering two rough Tanzanite stones valued at $3.4m sold another one for $2m on Monday morning.
The third discovery by Saniniu Laizer, who is a small-scale miner, weighed 6.3kg.
There was a lot of excitement from members of his community in the build up to the sale and hundreds were waiting from early morning to witness it, the BBC's Aboubakar Famau reports from the capital, Dodoma.
Many other small-scale miners were shocked by Mr Laizer's luck but also acknowledged that perseverance may have something to do with it, our correspondent adds.
Mr Laizer has promised to use the money from the finds to build a school and a health centre.
Tanzanite is only found in northern Tanzania and is used to make ornaments.
It is one of the rarest gemstones on Earth, and one local geologist estimates its supply may be entirely depleted within the next 20 years.
The precious stone's appeal lies in its variety of hues, including green, red, purple and blue.
Africa editor, BBC World Service
Activists in Tanzania say new rules that restrict online content are infringing on people’s freedom of expression.
Under the new legislation, organising, planning or even supporting any form of demonstration online is now illegal.
The new rules have also banned sharing of information about an infectious disease outbreak without government permission.
The Tanzanian authorities have removed rules governing hate speech on the basis of sexuality and gender.
Correspondents say the new rules also make it possible for people to be prosecuted for what they write on a shared instant messaging platform, such as a WhatsApp group.
Human rights groups say since President John Magufuli came to power five years ago the Tanzanian authorities have cracked down on the media, civil society organisations and individuals critical of the government.
Three African Americans have been explaining why they left the US to find a better life in Africa.
The funeral of Tanzania's former President Benjamin Mkapa is underway in his home in Lupaso, south of the country.
President John Magufuli is expected to lead mourners in the final journey of the former leader.
Mr Mkapa died on Friday after he had a cardiac arrest.
Tanzanians attending his funeral have started viewing his body.
The BBC's Sammy Awami has shared this photo of the ceremony:
Tanzania Broadcasting Corporation shared a video of the body viewing: