The 36-year-old, also an Olympic bronze medallist, was sanctioned along with relay team-mate Michele Santucci.

The Italian National Anti-Doping Organisation (NADO) had called for Magnini, who retired in December of last year, to be banned for eight years.

Magnini and Santucci, also suspended for four years, were investigated following allegations of "use or attempted use of doping products".

This was part of a probe into nutritionist and doctor Guido Porcellini, since banned for 30 years by the NADO for distributing illegal drugs.

Magnini's name was implicated in the investigation into the disgraced doctor, as it revealed certain products were due to be given to the swimmer.

According to reports, investigators conceded that he might not have even used or received them but determined there was enough evidence to ban him.

In response to the verdict, Magnini claimed he would appeal and labelled the allegations against him as "ridiculous".

"This sentence has had my name on it for a long time, that's why I'm feeling such anger," he said, according to Agence France-Presse.

"There is no proof."

The ruling followed a prolonged period of uncertainty for Magnini, winner of the 100 metres freestyle gold medal at the 2005 and 2007 World Championships.

Judges at a hearing into the matter, held in Rome last month, ruled that more time was needed to make a decision.

The initial allegations implicating Magnini, who claimed his Olympic bronze medal in the 4x200m relay at Athens 2004, were first raised last year.