The Fair Trade Commission is probing three key players in the domestic stent market – Abbott Korea, Boston Scientific Korea, and Medtronic Korea – for alleged bribery for physicians in exchange for stent sales.

The probe comes in six years after the anti-trust watchdog investigated the three companies for similar reasons in 2013.

The FTC on Monday raided the offices of Medtronic Korea and Boston Scientific Korea and looked into the companies until Tuesday. In January, the agency also raided Abbott Korea for illegal rebate allegations.

The FTC suspects that the three companies offered improper monetary benefits to doctors in breach of the fair trade rules for medical device transactions.

Both Medtronic Korea and Boston Scientific Korea admitted they were under FTC’s investigation.

The three stent makers were under probe by the FTC for similar charges in 2013.

While Medtronic Korea was acquitted, Boston Scientific Korea and Abbott Korea received a correction order on charges of providing hospitals and doctors with unfair economic benefits disguised as financial support for travel fees for overseas conferences.

The medical device industry is paying close attention to the result of the FTC’s investigation. If the FTC confirms that allegations of unfair economic benefits are right, the regulator might impose a punishment heavier than the one in 2014.

“The latest raid seems to be a follow-up of the January probe into Abbott. As the authorities enhanced legal sanctions against illicit rebates, they are likely to impose a stronger punishment, more than just penalties,” an official at a medical device company said.

The vascular stent market in Korea is estimated at 150 billion won, and multinational firms make 90 percent of the products.

Among multinationals, Abbott, Medtronic, and Boston Scientific are leading the stent market.