The nation’s antitrust watchdog said Wednesday that it will launch a large-scale investigation into unfair business practices at major department stores and supermarket chains next month.

The Fair Trade Commission also plans to revise a leniency program so that when two companies are caught price-fixing only the first declarer has its fines cut.

“We will look into how commission cuts, agreed in September, are carried out at 11 major retailers and whether there are any illegal business activities targeting smaller vendors,” FTC chairman Kim Dong-soo said in an interview Wednesday.

He added that authorities have already confirmed some cases in which retailers charge vendors additional costs for labor and promotion activities or raise commissions for those not subject to agreed fee cuts.

“We have built up a hotline to secretly crack down on the illegal practices of large retailers. The final result of the investigation will be announced in May,” he said.

He also hinted at a revision to the current leniency program that grants immunity for the first declarer of a price-fixing case, while the second gets a 50 percent cut in fines.

On Jan. 12, Samsung Electronics and LG Electronics were slapped with fines of 25.8 billion won ($22.9 million) and 18.8 billion won, respectively, for rigging prices of washing machines, flat screen televisions and laptop computers.

However, LG, the first declarer, was exempted from the fines, while Samsung saw its fines cut in half. The FTC is financially supporting a consumer class action lawsuit against the two companies.

“There are a growing number of companies that attempt to abuse the leniency program. We are planning to revise related regulations,” Kim said.

The FTC is expected to complete its ongoing investigations into Google and Apple soon, he said.

Google is under investigation for bundling its search engine with the Android operating system, while Apple is being investigated for forcing app developers to use its own payment system.

“With the influence of platform operators getting bigger, we will strengthen surveillance on this area for potential abuse of market dominance or unfair activities,” he said.

The FTC also will release a consumer price report of 13 items on monthly basis within the year, starting with pension insurance in April and franchise coffee houses in May.

By Lee Ji-yoon (jylee@heraldcorp.com)