OSI Systems, the maker of airport scanning systems, lost nearly a third of its value on Wednesday after short-seller Carson Block accused it of underhanded practices.

“We think this company is rotten to the core,” Block’s firm, Muddy Waters, said in a 19-page report, which was accompanied by a 10-minute video.

A potential $250 million contract OSI signed with Albania was likely obtained through a bribe, Muddy Waters claimed, citing the firm’s research and speculation in local media reports.

The short-selling firm also raised questions about a contract OSI has in Mexico, claiming it was “substantially overpriced and oversold in terms of capabilities.”

Late Wednesday, the company, based in Hawthorne, Calif., denied any wrongdoing.

“Our turnkey security inspection programs in Mexico and in Albania were the result of public tenders,” OSI said in a statement. It said it “would not customarily respond to misleading allegations from short sellers, [but] this particular report has had an undue impact in the public sphere and warrants a response.”

OSI shares fell 29.2 percent, to $59.52. Prior to Wednesday’s drop, the stock was up 10.4 percent for the year.