A Tanzanian opposition party, ACT, has accused the president of "broadcasting a select few statistics" to falsely claim that there's been a big drop in the number of coronavirus patients in hospitals.

President John Magufuli told an applauding church congregation on Sunday that there had been a "sharp decline", adding, "God has answered your prayers."

That was despite a report days before by the US embassy in Tanzania saying many hospitals had been "overwhelmed".

On Monday, the ACT said in a statement it "will not simply assume that the president is right in saying we are winning the battle against coronavirus, just because he says so".

It wants the government to release "the full set of data" on infection and death rates, and adds that the last such report was made more than a fortnight ago.

"Transparency is essential. President Magufuli must commit to this core principle of governance. He owes it to the people of Tanzania," the statement adds.