A set of three new photographs taken at the National Centre for Scientific Investigation in the Cuban capital Wednesday show the grey-bearded Castro, 83, smiling at workers and wearing a white tracksuit, the BBC reported quoting local media.
These pictures, taken with a worker's mobile phone, offer a rare glimpse of the reclusive leader who appears slightly stooped but otherwise healthy. Castro has not been photographed in public since July 2006, when he stepped down to reportedly undergo intestinal surgery.
The images were posted on the blog of two Cuban journalists Saturday, after a worker at the centre sent the pictures to one of them named Rosa Baez.
An additional five photos from the same event were published Saturday by the state-run media site Cubadebate, the CNN reported.
A comment from the unidentified worker accompanied the images, and said: "He is thin but he looks good, and according to our director, he is very good mentally."
Castro stopped, said hello and blew kisses to the employees, the worker said.
The pictures were also posted on the blog of Norelys Morales, a Cuban television journalist.
Castro has not been photographed in public since being taken ill in July 2006. He later handed over power to his younger brother Raul, 79.
However, the only updates on his health have come from visiting dignitaries who were allowed to meet him. The state has still not disclosed what he suffers from, or whether he is recuperating.
DPA adds: The former president commemorated the 45th anniversary of the centre's founding in sports attire and held animated conversations with the managers and workers, the Cubadebate website said.
"When the word got out that the commander-in-chief was here, the workers came together spontaneously to offer warm tribute, which Fidel returned with words of gratitude," Cubadebate said.