They are the first reported Ebola cases outside West Africa since the outbreak there began, although it is not clear if they are directly linked to that outbreak.

So far 1,427 people have died from the virus.

The speed and extent of the outbreak has been “unprecedented”, the World Health Organization (WHO) says.

An estimated 2,615 people in West Africa have been infected with Ebola since March.

There is no known cure but some affected people have recovered after being given an experimental drug, ZMapp. However, supplies are now exhausted.

Also on Sunday, a British health worker infected with Ebola in Sierra Leone was flown back to the UK on an RAF jet. It is the first confirmed case of a Briton contracting the virus during the current outbreak.