Nigeria, the most populated country in Africa, on Saturday tightened restrictions in three states on places of worship, airports and bars to try and protect its population against the new coronavirus.

In Lagos state, Abuja and Ogun, churches, mosques, social gatherings, football viewing centres and night clubs must restrict attendance to 50 people, according to new regulations drawn up by the Presidential Task Force on COVID-19.

Three airports, including one serving oil centre Port Harcourt will no longer take flights from abroad, but the country's two main airports, in Lagos and the capital Abuja, "will remain opened to and accept ," a statement said.

Congregations at places of worship are hereby restricted to a maximum of 50 persons at any given time," it added.

The Nigerian Railway Corporation also announced a suspension of rail links from Monday, March 23.

In Lagos, a sprawling, densely-populated city of 20 million people, a municipal decree on Friday had already closed bars, restaurants and night clubs.

Nigeria has recorded around a dozen confirmed cases of new infections, but testing has been limited.