"Keita was allowed to travel abroad for treatment and will soon leave for the UAE or France," the source said.
"The leader of the National Committee for the Salvation of the People, Assimi Goita, had visited Keita to check his condition, and doctors affirmed the necessity to transfer him abroad for treatment as soon as possible," the source noted.
Keita was toppled by the military junta in late August.
Earlier in the week, the 75-year-old ex-Malian leader, who suffered several heart attacks, was taken to a private clinic in the capital of Bamako, as his health condition deteriorated, according to his inner circle.
After Keita announced his resignation and the dissolution of parliament, the rebel leaders established the National Committee for the Salvation of the People (CNSP) as Mali's main governing body.
Keita’s release had been the subject of negotiations between the CNSP and Western African regional bloc ECOWAS, as well as demands by leaders of countries across the world.