Nigeria will extend lockdowns in Lagos, Abuja and Ogun states for an additional 14 days to combat the new coronavirus, President Muhammadu Buhari said in an address to the nation on Monday.

Initial 14-day lockdowns in the three areas began on March 30. Buhari said it was crucial to extend the lockdown due to an "alarming" increase in positive cases in a number of states.

"It is a matter of life and death," Buhari said of the nation's response. "The repercussions of any premature end to the lockdown action are unimaginable."

There are currently 323 confirmed cases of the virus in Nigeria, 71% of them in Lagos and the capital territory of Abuja, and ten people have died from the virus.

When the lockdowns were announced on March 29, the nation had 97 confirmed cases.

Nigeria, with 200 million people, is Africa's most populous nation. 20 million of those people reside in the megacity of Lagos.

Health experts have raised alarms over the impact of any spread in the virus, warning that the country's unprepared and underfunded healthcare system could quickly become overwhelmed.