Former Tour de France winner Marco Pantani has died at the age of 34, according to media reports in Italy.
Italian news agency Ansa reported on Sunday that his body was found in a hotel room in Rimini.
The cause of his death was still unknown, although police reports said no violence was involved.
The coach of the Italian national cycling team Franco Ballerini was quoted as saying: "It's something that is so huge, it doesn't seem true."
Pantani, a fine climber nicknamed 'The Pirate' and who regularly wore colourful bandanas over his shaved head, won the Giro d'Italia in 1998 and then the Tour de France in the same year.
He was the first Italian to win the Tour de France since Felice Gimondi in 1965.
He was the subject of a major scandal in 1999 when he was thrown out of the Tour of Italy. Leading the race, he failed a test for haematocrit -- an indicator, though not proof, of the use of performance-enhancing drugs.
He was also banned in 2002 for using insulin during the previous year's Giro.
He rode in the 2003 Giro, finishing a disappointing 14th, and was later treated in a drugs and depression clinic. His team Mercatone Uno were not invited to take part in the centenary Tour de France last year.