The British nurse being treated for Ebola in London is no longer in a critical condition, the hospital has confirmed.

In a statement released today, the Royal Free Hospital says it is "pleased to announce that Pauline Cafferkey is showing signs of improvement and is no longer critically ill. She remains in isolation as she receives specialist care for the Ebola virus."

Cafferkey was diagnosed with Ebola on December 29 after returning to Britain from Sierra Leone, where she had been working for the charity Save the Children at a treatment centre outside the capital, Freetown.

Cafferkey is the first person to have been diagnosed with Ebola on British soil.

The Royal Free, Britain's main centre for Ebola cases, successfully treated British aid worker William Pooley with the experimental drug ZMapp after he was flown back to Britain in August.

Ebola is transmitted through bodily fluids, and the hospital said it was treating Cafferkey inside a specially designed tent around her bed with controlled ventilation to reduce the risk of further infections.

Following her diagnosis, David Cameron tweeted that he was praying for the nurse and her family.

In late December, when Cafferkey first arrived in hospital, the Archbishop of Canterbury Justin Welby showed his appreciation for those working to combat the virus, writing: "we owe them thanks and respect", and asked for continued prayers.

The West African Ebola outbreak was first identified in Guinea's remote southeast in early 2014. Guinea, Sierra Leone and Liberia have borne the brunt of the 20,000 infections and nearly 8,000 dead.

In December Sierra Leone's government announced it was banning public celebrations over Christmas and New Year to try and prevent its spread.

Additional reporting by Reuters