Castro, 80, temporarily handed power to his brother and defence chief Raul, 75, on July 31, four days after undergoing surgery.
He has only been seen in videos and pictures since July, but he has published in the last two weeks three articles railing against George Bush, the US president, in a sign that he is still closely following current events.
It is the first time that the Communist stalwart has given up the reins of government since his revolution toppled the government of Fulgencio Batista in 1959.
On March 20, Yadira Garcia, Cuba's basic industry minister, said Castro was already involved in leadership of the country by taking part in major political and economic decisions.
"The expectation we all have is that, yes, we will soon have him with us in a more active way," she said.
That same day Colombian daily El Tiempo published a photograph of Castro chatting to Nobel prize-winning Colombian writer Gabriel Garcia Marquez, a longtime friend, in Cuba the week before.