Fidel Castro told thousands of admirers he wasn't well enough to join them to launch the delayed five-day celebration of his 80th birthday, raising new questions about the health of the ailing Cuban leader. The message from Castro, which was read to a crowd of 5,000 at the Karl Marx Theater and on state TV, indicates that he is far from recovered from a mysterious ailment that forced him on July 31 to turn over power to his brother, Defense Minister Raul Castro. The Cuban leader turned 80 on August 13 but delayed his birthday celebrations as he recovered from surgery two weeks earlier for intestinal bleeding. Castro, who has not been seen in public for four months, wanted the delayed birthday celebrations held on December 2, to coincide with the 50th anniversary of the date that he and fellow rebels landed by boat in Cuba to launch their revolution. Clearly Castro felt he would be sufficiently recuperated from the intestinal ailment by now to participate in the delayed celebrations. But his announcement Tuesday raises doubts about whether he will appear at all. In a message read to luminaries who traveled from abroad and thousands of other admirers at the celebration's kickoff, Castro said doctors told him he was not in condition to meet with a large crowd. "I direct myself to you, intellectuals and prestigious personalities of the world, with a dilemma," said Castro's note. "I could not meet with you in a small locale, only in the Karl Marx Theater where all the visitors would fit, and I was not yet in condition, according to the doctors, to face such a colossal encounter." "My very close friends, who have done me the honor of visiting our country, I sign off with the great pain of not having been able to personally give thanks and hugs to each and every one of you," Castro wrote. The crowd responded with a standing ovation. More than 1,300 politicians, artists and intellectuals from around the globe are determined to honor the man who governed this communist-run island for 47 years. Presidents Evo Morales of Bolivia and Rene Preval of Haiti have confirmed their attendance, along with former Ecuadorean President Rodrigo Borja and Nicaraguan President-elect Daniel Ortega. Also expected are Argentine soccer great Diego Maradona, South African singer Miriam Makeba and Colombian Nobel laureate Gabriel Garcia Marquez. Nobel Peace Prize winner Adolfo Perez Esquivel, an Argentine human rights campaigner, was also expected. Brazilian poet Thiago de Mello, Ecuadorean writer Jorge Enrique Adoum and Nicaraguan politician Tomas Borge arrived over the weekend. Castro's good friend and political ally Venezuelan President Hugo Chavez won't be able to come; he is up for re-election on December 3. But Chavez has promised to dedicate his electoral victory to Castro. Cuban officials insist Castro is recovering, but US officials say they believe he suffers from some kind of inoperable cancer and won't live through 2007. His ailment is a state secret. Castro has been seen by the public only in photos and videos since he announced he was temporarily ceding power to his brother. Also Tuesday, the new San Geronimo College, focusing on historical renovation, archaeology and related disciplines, was dedicated in Old Havana in honor of Castro's birthday. Inaugurating the college, City Historian Eusebio Leal said Castro was with them in spirit. "The fact that he is not here doesn't mean that he is far from our hearts," said Leal, who also sits on Cuba's National Assembly, or parliament. Other birthday activities include a three-day academic conference starting Wednesday, a concert with Cuban and other Latin American artists on Friday night, and an art exhibit. More than 300,000 people are expected at a military parade on Saturday, the anniversary of the start of the revolution that ultimately triumphed on January 1, 1959.