Neither Cuban nor Venezuelan authorities have disclosed where Chavez is being treated.

The government in Havana has remained tight-lipped about the treatment of their close ally, who sends Cuba millions of barrels of oil at deeply discounted prices.

Many Cubans are worried that Chavez's illness could mean an end to those generous subsidies. The island's economy never fully recovered after the Soviet Union cut their huge aid package following the fall of the Berlin Wall.

On Tuesday, panelists at a discussion about a new documentary on Chavez in Havana touched upon the leader's ill health.

Venezuela's military attache to Cuba appeared to tear up as he discussed Chavez's cancer.

"My commander in chief has been the man to take on problems," Col. Eldan Rafael Dominguez Fortty said. "We have overcome every obstacle, and now with this battle to survive, he will figure that out, too."