Prosecutors in the northern city of Udine launched the investigation on Tuesday, a day after police confiscated around 50 boxes containing unidentified substances from the rooms of the hotel in Lignano Sabbiadoro, where Asafa Powell (pictured above) and Sherone Simpson had been staying.

Police said Powell, a former 100-meter record holder, Simpson, and their Canadian physiotherapist, Chris Xuereb, had since left the town, where the sprinters had been training. All three had been questioned by police following Monday's raids.

Substances still to be tested

The three are being investigated under an Italian law which bans the supply and ingestion of banned substances. However, police still don't know what exactly was in the boxes they seized.

"The substances we seized still have to be tested," an unnamed police officer told the AFP news agency. "We began the investigation because of the positive test results that were announced. We are not planning to conduct our own (doping) tests (on the sprinters)," he added.

Powell, who held the 100-meter record before Usain Bolt broke it in 2008, and Simpson, who won gold in the women's 4 x 100 relay at the 2004 Olympics in Athens, were among five athletes to test positive for the stimulant oxilofine at the Jamaican championships last month.

The news of their positive tests came on the same day that US sprinter Tyson Gay revealed that he too had tested positive for a banned substance and would pull out of next month's world championships in Moscow.

pfd/tj (AP, AFP, Reuters)