An opposition leader said on Tuesday Tanzanians had become fearful due to lack of information about the health of President John Magufuli, who has not been seen in public for more than two weeks, and citizens had the right to know about his condition.

Speculation in East Africa is rife that Magufuli, 61, a vocal Covid-19 sceptic, is ill with the virus, though his vice president said on Monday that the country was safe and citizens should ignore rumours from outside the country.

"It is important for the government to inform the public about the president’s health to reduce ongoing fear," Zitto Kabwe, leader of the ACT-Wazalendo party, said in a statement.

"The president's health is not supposed to be a secret," he said, recalling that Tanzanians received regular updates on the health of two former presidents, Benjamin Mkapa and Jakaya Kikwete, when they were abroad for medical treatment.

Kabwe said Tanzania's constitution calls for the speaker of the national assembly to make information public on the president's health.

Government spokesperson Hassan Abbasi did not return calls and messages seeking comment.

Another opposition politician, Tundu Lissu, who lost an election last year to Magufuli, said last week from exile in Belgium that the president is in India receiving medical treatment for the virus and is in a serious condition.

India's immigration service records do not show anybody by the name of John Magufuli entering the country, and air ambulance flight records do not show a flight from East Africa since February 1, an Indian government source told Reuters on Tuesday.

Magufuli has mocked global panic over the Covid-19 pandemic and played down the virus' threat in Tanzania. He has denounced Covid-19 tests, denounced vaccines, and opposed mask-wearing, instead urging his people to put faith in prayer and try remedies such as steam inhalation.

Kabwe, the opposition leader, also called on the government to release people arrested for questioning the president's health. Police have arrested four people in the country since last week for allegedly spreading false information about the sickness of political leaders, according to the police, who did not mention the president's name when referring to the arrests.