MADRID (AFP) - A Spanish nurse may have become infected with Ebola when she touched her face with a glove as she removed her protective suit after treating a missionary who had the deadly virus, a doctor treating her said on Wednesday.

Health officials say Teresa Romero twice entered the room of Spanish missionary Manual Garcia Viejo - once to clean him and the second time after he died on September 25, just days after being repatriated from Sierra Leone.

Doctor German Ramirez of Madrid's La Paz-Carlos III hospital said Romero told him she remembers she touched her face with her gloves as she removed her protective suit after leaving the quarantine room at the hospital where the missionary was being treated.

"She thinks she remembers that it was during the first time she entered the room but we should continue to look into it," he told reporters gathered outside the hospital.

"It seems like it was the gloves. The gloves touched the face," Ramirez said, adding the infected nurse had authorised him to speak to the media.

"It is possible that this was not a mistake as such. It could simply be an accident and logically, probably, she could not remember at the beginning because of the state of her health." Romero had said in an interview published in El Mundo on Wednesday that she had "no idea" how she could have contracted the virus.

But in an interview Wednesday in the online edition of El Pais newspaper, she said she thought she may have become infected when she removed her protective suit.

"I think the mistake was when I removed the suit. I see it as the most critical moment in which it could have happened but I am not sure," she told the newspaper by telephone from her room at the hospital where she is being treated in isolation.

Romero is the first case of Ebola being transmitted outside of West Africa, where a months-long outbreak has killed nearly 3,500 people and infected at least twice as many.