A Scottish nurse, who recovered from Ebola but then suffered life-threatening complications from the virus persisting in her brain, has been admitted to hospital for a third time, officials said on Tuesday.

Pauline Cafferkey contracted Ebola in December 2014 when she was working in a treatment facility in Sierra Leone at the height of an epidemic of the disease which swept through three countries in West Africa.

Cafferkey was being transferred on Tuesday from the Queen Elizabeth University Hospital in Glasgow to the Royal Free Hospital in London, which has a unit that was specially set up to deal with any Ebola cases in Britain.

"We can confirm that Pauline Cafferkey is being transferred to the Royal Free Hospital due to a late complication from her previous infection by the Ebola virus," the hospital said in a statement.

"She will now be treated by the hospital's infectious diseases team under nationally agreed guidelines."

After being transferred from Sierra Leone to Britain, Cafferkey initially recovered from the Ebola hemorrhagic fever and was sent home in January last year.

But in October she fell ill again and doctors found the virus was persisting in tissues in her brain. They later said she had developed meningitis caused by the Ebola virus - the first known such case.

She was treated with an experimental antiviral drug known as GS5734 being developed by US drugmaker Gilead Sciences, although doctors did not disclose whether they thought the drug had improved her condition.

She was last discharged from the Royal Free Hospital in November.

The two-year Ebola epidemic in Sierra Leone, Guinea and Liberia killed more than 11,300 people, according to the World Health Organisation.