Al-Saadi Gaddafi, the son of Libyan leader Colonel Muammar Gaddafi who plays for Serie A side Perugia, has tested positive for norandrosterone, Italian sporting authorities say.

Italy's Olympic Committee (CONI), the nation's sporting watchdog, said in a statement that Gaddafi had failed a regular doping test at a match between Perugia and Reggina on October 5.

Norandrosterone is a metabolite of the steroid nandrolone.

Meanwhile, Perugia president Luciano Gaucci, who controversially signed Gaddafi in June this year, sought to play down the drugs test, explaining that the player had taken the banned substance by mistake.

"Gaddafi's been taking medicines to treat backache. He has problems with his back and has been visiting his doctor in Germany for months," Gaucci was quoted as saying on La Gazzetta dello Sport's website.

"It's no secret that certain drugs can contain prohibited substances."

'DESERVED REWARD'

Since his highly publicised arrival at Perugia, the 30-year-old striker has yet to play in Serie A and has made it to the bench on just two occasions.

"That Sunday, against Reggina, Gaddafi went on the bench even though he knew that he wasn't fit to play," continued Gaucci.

"He deserved a reward for all the work he's done and he wanted to stay close to the team. He's no more to blame than the club is.

"We had told him to get treatment here in Italy but he preferred to go abroad.

"It's his health -- we certainly couldn't stand in his way. I don't know for sure if he saw a specialist sports doctor."

Gaddafi now faces immediate suspension by the Italian Football Federation until the results of a second B test are known.

He is the third Serie A player to be revealed in three weeks to fail a drugs test.

Parma midfielder Manuele Blasi and Inter Milan striker Mohamed Kallon both tested positive for nandrolone and are awaiting the results of B tests.

If those prove positive all three face a ban from the game of up to two years, although previous bans in Italy have been for a period of four to six months.