Pauline Cafferkey, the British nurse who contracted Ebola has 'stabilised' in hospital, according to the British Health Secretary.

British Health Secretary Jeremy Hunt gave the update as Save the Children said it was urgently reviewing its Ebola safety protocols.

Ms Cafferkey was diagnosed with the deadly virus when she returned to Britain after volunteering with the charity in Kerry Town, Sierra Leone.

She is in an isolation tent at the Royal Free Hospital, in North London, and is being treated with an experimental anti-viral drug.

Save the Children is trying to find out whether the 39-year-old contracted the virus while at the Ebola Treatment Centre or in the community, but said it "may never be possible to be 100% sure" how she was infected.

The charity said in a statement: "Save the Children has been conducting a review since Pauline Cafferkey was confirmed as Ebola positive.

"The Serious Event Review (SER) is looking at how the patient might have contracted Ebola by reviewing training, safety protocols, how protective equipment is used, and working practices.

"The findings of the review will be considered by a panel including independent health experts, which will support Save the Children and make recommendations for any actions if necessary."

Ms Cafferkey was part of a 30-strong team of medical volunteers deployed to Sierra Leone by the UK Government in November and had been there for three weeks before returning home for a break.

In a statement to the Commons, Mr Hunt praised Ms Cafferkey and her colleagues for their "exceptional bravery and compassion they showed in joining the battle against Ebola".

He added: "The work done by Pauline and her colleagues is not just helping to save thousands of lives in Africa, it's protecting the UK from potentially disastrous consequences if the disease spreads beyond the countries where it has currently taken hold."

He said he had spoken to the doctor leading Ms Cafferkey's care at the Royal Free Hospital.

"As has been reported, Pauline's condition has deteriorated to a critical state although she stabilised yesterday and continues to receive the best possible care," he said.

Mr Hunt also said the UK has tightened steps for dealing with possible Ebola patients - and that the extra measures have been in place since 29 December.

"We have ... strengthened our guidance to ensure that anyone from a high-risk group who feels unwell will be reassessed, advice will be immediately sought from an infectious diseases specialist and the passenger will be referred for testing if appropriate," he told MPs.

"Even if someone isn't displaying symptoms but says they are feeling a bit under the weather, then we would isolate them if they are in the high-risk category."

Ms Cafferkey, who works at Blantyre Health Centre, in South Lanarkshire, first raised concerns about her condition when she returned to Heathrow Airport last Sunday.

Despite undergoing seven temperature checks she was given the all-clear to fly to Glasgow where she lives.

The following morning she was diagnosed with Ebola and placed in isolation at Gartnavel Hospital in Glasgow before being flown to London.