It provided no further details.
Fidel Castro ruled Cuba as a one-party state for almost half a century before handing over the powers to his brother Raul in 2008.
His supporters praised him as a man who had given Cuba back to the people. But his opponents accused him of brutally suppressing opposition.
In April, Fidel Castro gave a rare speech on the final day of the country’s Communist Party congress.
He acknowledged his advanced age but said Cuban communist concepts were still valid and the Cuban people “will be victorious”.
“I’ll soon be 90,” the former president said, adding that this was “something I’d never imagined”.
“Soon I’ll be like all the others, “to all our turn must come,” Fidel Castro said.