Megrahi, who is suffering terminal prostate cancer, was sent home to Libya to die after medical experts concluded in a report on July 30 he had just three months left to live.
The time span was crucial because only prisoners with three months or less to survive are eligible for release on compassionate grounds.
But three months on from Prof Sikora's diagnosis, Megrahi is well enough to "walk and talk" and shows no sign of deterioration, according to a senior source involved in his release.
The source told The Sunday Telegraph: "His condition has not deteriorated in three months.
He is pretty much in the same way as he was when this all started. He is just as he was. There is nothing that leads anyone to believe he is in any different condition to when he left Scotland."
A frail-looking Megrahi was able to walk with the aid of a stick when he arrived back in Tripoli, amid jubilant scenes in the Libyan capital that caused widespread anger in the US and elsewhere.
The source told The Sunday Telegraph that Megrahi, 57, is still able to talk and walk with a stick, contradicting claims from his family that he is bedridden, unable to speak and near to death.
"He can still walk and he can still talk," said the source.