Fidel Castro chatted live via speakerphone with graduating medical students in Nicaragua in the latest of a series of media events showing off the former Cuban leader looking more robust.

The 83-year-old Castro, who hasn't been seen in public since falling ill three years ago, called Thursday during the graduation ceremony to congratulate the 44 doctors who had studied in Cuba.

Nicaraguan President Daniel Ortega interrupted a graduation speech to put Castro's call on a speaker for the crowd to hear.

"I'm a great admirer of doctors, and it makes me very happy that a group of graduates is getting together," Castro told Ortega in the brief call.

It was Castro's first publicly broadcast phone call since 2007, when he exchanged praise and jokes with Venezuelan President Hugo Chavez via telephone on Chavez's Sunday television and radio program.

Despite periodic rumors that he is on his death bed, a healthier-looking Castro has recently emerged in photos and video, meeting with Latin American leaders and student and church delegations.

He appeared on state television Sunday for the first time since June 2008, meeting with a group of Venezuelan law students. The broadcast showed Castro, looking heavier and rested, talking with the students at an undisclosed location.

Castro ceded power to his brother Raul when he fell ill and formally stepped down as president in February 2008.