Former world 100-meter record-holder Asafa Powell and 100-meter Olympian Sherone Simpson, the medal winner, confirmed they had tested positive for oxilofrine, but denied in statements they had knowingly taken the stimulant, The Jamaica Gleaner reported Monday.
"I have never knowingly or willfully taken any supplements or substances that break any rules," Powell said.
The sprinter said he was "reeling from this genuinely surprising result."
Simpson, apologizing to her family, fellow athletes "and the rest of Jamaica," said, "I am deeply sorry for any hurt or embarrassment this positive test may cause, and my team and I will do everything we can to get this issue dealt with as best we can."
Traves Smikle and Allison Randall, both discus throwers, also tested positive, the report said.
Police in Lignano, Italy, searched the hotel rooms of Powell, Simpson and one of their coaches Monday and seized foreign medicines and some diet supplements, ANSA news agency reported.
Authorities described the seizures as a precautionary measure.
One of Powell's coaches was arrested Sunday by Italian police, Jamaican media reported.
Last month, Veronica Campbell-Brown tested positive for diuretics.
The doping news came less than a month before the start of the IAAF World Championships in Moscow.