Havana, Sep 3 (EFE).- Dressed in olive drab, Fidel Castro spoke Friday for 45 minutes to thousands of students in the first massive event open to the public at which he has appeared since he became ill four years ago and handed over the presidency to younger brother Raul.

Wearing glasses and a green military cap, Fidel, 84, remained standing during the whole speech, despite the mobility problems he mentioned in a recent interview with the Mexican daily La Jornada.

He only complained twice, once to ask for some water and another time because he was facing into the sun and it kept him from continuing his speech, which was read and not extemporaneous as was his custom before his illness.

The thousands of students crowding the long stairway at the University of Habana had been waiting since 4:00 a.m. to see their "maximum leader," who appeared punctually at 7:30 to teach them about the risks threatening humanity.

The danger of nuclear war has become a subject that practically monopolizes Fidel's public appearances, and both in his interviews and in his written "reflections," he avoids referring to Cuba's internal situation, which many have interpreted as a division of labor with Raul.

Fidel expressed his concern Friday that "the world is deliberately hiding this reality (nuclear war) from itself, and it remains up to Cuba to undertake the difficult job of warning humanity of the real danger it is facing, and we must not be faint-hearted in this task."

He spoke at length about the number of atomic weapons and the amount of uranium in the world, and about the possibilities that Israel will attack Iran and block the Strait of Hormuz, a potential choke-point for oil shipments.

Several students dozed off while others chatted away, more concerned about the sweltering heat of the sun than about a nuclear catastrophe.

The subject of the speech did not seen to excite the young audience, which applauded politely as the man spoke who has ruled their destinies all their lives.

Castro was understanding, and after talking for 40 minutes, he urged the students to bear with him: "Good news, I'm almost finished."

But if he didn't complain, much less did the students who agreed to speak with reporters and for whom the drowsiness, thirst and fatigue were all to the good.

"We get goose-pimples and our heart races when we see Fidel standing before us, and see how he talked to us and keeps on fighting...we will always look upon him well," Carlos, 16, who, as a high school student, wasn't required to attend but didn't want to miss the chance of seeing him, said.

"He's very healthy and very strong - I think we'll have the commander around for some time," said Dunieski, who works at the University of Computer Sciences, to which her friend Yenny added: "He's what we need right now, this talk alerts and inspires us."

In the audience were a number of foreign students studying in Cuba on scholarships, many carrying the flags of their countries, such as Abdon, a Bolivian attending medical school, who vowed to make it his mission to carry home the message received this morning.