The Nigerian passenger who was taken to a Madrid hospital from an Air France plane by police-escorted ambulance over fears he was suffering from Ebola has tested negative for the disease, the Spanish government said on Friday.

Spain is on high alert for the disease after Romero, a nurse who cared for two Ebola-infected priests before they died, became the first person to contract the virus outside West Africa. She is gravely ill but stable.

Although the two people tested negative for the disease initially, they must have another test within 72 hours in order to be given the all clear, the government said.

The United States, which is deploying up to 4,000 troops to West Africa to help contain the disease, has asked Madrid for permission to use U.S. military bases in Spain in its operation, a Spanish Defense Ministry source said on Thursday.

A decision is due to be announced on Friday when Spanish Defense Minister Pedro Morenes meets his U.S. counterpart Chuck Hagel in Washington. Madrid was set to agree to the request to use the bases at Rota near Cadiz and at Moron de la Frontera near Seville in southern Spain, the source said.