A British nurse diagnosed with Ebola earlier this week is being treated with blood plasma from a survivor of the virus and an experimental antiviral drug, the London hospital treating her said on Wednesday. 

Pauline Cafferkey, a health worker who returned from an Ebola treatment center in Sierra Leone on Sunday, became the first person to be diagnosed with the deadly virus on British soil, after complaining of a raised temperature.

"We have decided to treat her with two things, the first of which is convalescent plasma, that means a product taken from the blood of another patient who has recovered from Ebola," said Dr Michael Jacobs of London's Royal Free hospital.

The plasma, which would contain antibodies to help fight the disease, was selected from a Europe-wide pool, donated by survivors of the disease, he told reporters, declining to name the specific donor.

"The second thing we're giving her is an antiviral drug, it's an experimental antiviral drug," Jacobs said. "She's very well aware it's an experimental treatment."

Jacobs said no supplies were available of the drug ZMapp, which was used at the same hospital to help successfully treat a patient, William Pooley, who was diagnosed abroad and flown home for treatment earlier this year.

He declined to name the experimental drug being used on Cafferkey but said it had previously been used to treat Ebola patients, as well as other illnesses.

Jacobs said that although Cafferkey was feeling ill, she was as well as could be hoped for at such an early stage. But he stressed the unpredictable nature of Ebola and said the hospital would expect to have a clearer idea of her progress in a week's time. The patient was sitting up, reading and eating a little and had been visited by her family, who communicated with her via an intercom.