Mariela Castro. AFP PHOTO

"I can't imagine in graphic terms what will happen (after Fidel's death). But I feel a unity, such as that which exists in families that unite when there are problems," she told Portuguese news weekly Visao.

"I think that in this case the family is already united and we will support the new leaders of the revolution who will fill the void left by Fidel," added Mariela, whose father Raul Castro is the current de facto leader of the country.

"When you see the people's spirit, you know this is going to continue. With Fidel, with Raul or others, and with other generations, a sovereign Cuba will continue, a Cuba of socialism," said Mariela, a leading academic and campaigner for gay and lesbian rights in Cuba.

Fidel Castro, 80, underwent an operation on July 27. He handed over power temporarily to his brother and defense chief, Raul Castro, 75, four days later.

The iconic elder Cuban leader, who has been in power since 1959, has not been seen in public since his reported intestinal surgery. His prolonged absence from the public eye has fueled speculation that he is terminally ill.