The US has announced it is expanding its curbs on immigration to include six more countries, including Nigeria, Africa’s most populous nation.

Citizens from Nigeria, Eritrea, Sudan, Tanzania, Kyrgyzstan and Myanmar will now be blocked from obtaining certain types of visas.

People from those countries will still be able to visit the US as tourists.

In 2018 the US issued twice as many immigration visas to Nigeria than to the other five nations combined.

An official said the new measures were the result of failures by the six countries to meet US security and information-sharing standards.

“These countries, for the most part, want to be helpful but for a variety of different reasons simply failed to meet those minimum requirements that we laid out,” acting Homeland Security Secretary Chad Wolf told reporters on Friday.

He said officials would work with the countries on bolstering their security requirements to help them get off the list.