BAMAKO, April 4 (Reuters) - Mali said it had identified its first possible cases of Ebola since the start of an outbreak in neighbouring Guinea, adding to fears that the deadly virus was spreading across West Africa.

More than 90 people have already died in Guinea and Liberia in what medical charity Medecins Sans Frontieres (MSF) has warned could turn into an unprecedented epidemic in an impoverished region with poor health services.

Foreign mining companies have locked down operations and pulled out some international staff in mineral-rich Guinea. French health authorities have also put doctors and hospitals on alert in case people travelling to and from former colonies in the region pick up the disease.

Three people in Mali had been placed in quarantine and samples sent off to Atlanta in the United States for tests, the government said on state television late on Thursday.

"A high-speed intervention team has been created to follow the evolution of the situation on the ground," the statement said. It added that the health of the three suspected victims was showing signs of improving.