Image caption Fidel Castro had not been pictured in public since falling ill in 2006

New photographs have emerged showing Fidel Castro greeting workers in a rare public appearance.

The images of a grey-bearded Castro, 83, smiling and wearing a white tracksuit, offer a rare glimpse of the reclusive former Cuban leader.

Mr Castro appears slightly stooped but otherwise healthy in the four pictures, which were reportedly taken with a worker's mobile phone.

He had not been photographed in public since falling ill in July 2006.

The latest images, taken at a scientific think tank in Havana, were posted on the blog of two Cuban journalists on Saturday.

They were taken at the National Center for Scientific Investigation in the capital on Wednesday.

'Blowing kisses'

A worker at the centre reportedly sent the pictures to Rosa Baez, a journalist who works for official Cuban media, who posted them on her blog.

A comment from the unidentified Cuban worker accompanied the images.

"He is thin but he looks good, and according to our director, he is very good mentally," it read.

Mr Castro stopped, said hello and blew kisses to the employees, the worker added.

The pictures were also posted on the blog of Norelys Morales, a well-known Cuban television journalist.

Castro had not been photographed in public since being taken ill in July 2006. He was forced to hand over power - first temporarily, then permanently - to his younger brother Raul, 79.

The only updates on his health come from visiting dignitaries who have been able to meet him. Exactly what he suffers from, and where he is recuperating, remain state secrets.

Mr Castro himself said last year that he did not think he would see Barack Obama re-elected in 2012 - although it was not clear whether he was referring to his own life expectancy or the staying power of the US president.