Doctors in Nigeria's capital, Abuja, have gone on an "indefinite strike" over delayed pay and unsafe working conditions.

The announcement came just after Nigeria, Africa's most populous nation, confirmed a third case of Covid-19.

The president of the Abuja branch of the doctor's association, Roland Aigbovo, said it was a "difficult decision".

But members had not been paid their salary for two months despite repeated "warnings and ultimatums", he said.

The problems stem from a new payroll system introduced by the authorities in Abuja.

Other health workers at government-run hospitals in the city were also affected by the pay dispute and would be joining the strike in 48 hours if their demands were not met, Mr Aigbovo said.

Nigeria reported sub-Saharan Africa's first case of coronavirus in February.