Liberia has confirmed two patients have tested positive for the deadly Ebola virus, which is already believed to have killed at least 70 people in neighbouring Guinea.
Walter Gwenigale, Liberia's health minister, told the Associated Press news agency late on Sunday that one patient was married to a Guinean man and had returned ill from a recent trip there. She died in Lofa County.
The second patient is the sister of the dead woman. Gwenigale said she is alive and has been isolated in a medical centre outside of Monrovia, declining to give further details "because we don't want to cause panic".
Guinea confirmed last week that dozens of victims of hemorrhagic fever in the country's southern region had tested positive for Ebola. Cases have also been confirmed in the capital, Conakry.
Senegal on Saturday said its border crossings to Guinea would be closed "until further notice", while Sierra Leone has also reported suspected cases of the disease.
No treatment or vaccine is available for Ebola, a highly infectious and virulent disease which can cause uncontrollable bleeding. The Zaire strain detected in Guinea, first recorded 38 years ago in what is now the Democratic Republic of Congo, has a 90 percent death rate.
It can be transmitted to humans from wild animals, and between humans through direct contact with blood, bodily fluids or the unprotected handling of contaminated corpses.