Two-time world champion swimmer Filippo Magnini reportedly is facing a ban of up to eight years for doping.
The Gazzetta dello Sport is reporting Italy's anti-doping prosecutor has requested an eight-year ban for Magnini and a four-year ban for his relay teammate Michele Santucci.
Nado Italia, Italy's anti-doping authority, has declined to comment on the case as it is ongoing.
Magnini, who is retired, and Santucci were questioned last October by anti-doping authorities over their relationship with nutritionist Guido Porcellini. He is being investigated for allegedly distributing illegal drugs.
The Gazzetta reported on Wednesday that the prosecutor was also investigating the swimmers for use of banned substances.
Both maintained they had done nothing wrong and a lawyer for the swimmers would not comment.
A ruling is expected in September.
Magnini, who won the 100-metre freestyle at the 2005 and 2007 world championships, has never tested positive and is adamant he has never doped. He was an outspoken critic of doping throughout his career, having taken part in an "I am doping free" initiative.
Santucci teamed with Magnini when Italy won bronze in the 4x100m relay at the 2015 worlds.
Porcellini has previously been sentenced in two other cases, for cocaine trafficking and for domestic abuse.
