Fair Trade Commission Chairman Han Ki-jeong speaks during a press conference at Government Comlex Sejong, Monday. Yonhap

The nation's antitrust watchdog plans to revise key fair trade regulations to impose stricter oversight on online platform companies, which continue to exert unfair and excessive market influence, Fair Trade Commission (FTC) Chairman Han Ki-jeong said, Monday.

The move is a key part of the watchdog's policy agenda, driven by increasing demands for stricter penalties against platform companies following the sudden collapse of two formerly popular e-commerce firms, WeMakePrice and TMON.

According to the FTC, it will slap stricter regulations against dominant platform firms by imposing fines of up to eight percent on sales generated from their anti-competitive business practices. The figure is an increase of two percentage points from its earlier guidelines.

The watchdog also decided not to push ahead with the pre-designation of market-dominant business players amid strong backlash from the industry. However, it introduced a standard for such players, so that such firms are subject to heightened regulatory scrutiny by the FTC afterwards.

Under the updated rule, a platform company, with more than 60 percent market share and with over 10 million users, will not be prohibited from engaging in four anti-competitive practices, such as cross-selling their online services. When less than four firms obtain a combined market share of 85 percent, and each of them has more than 20 million users, they too will also face the same scrutiny under the revised rule.

Nevertheless, the watchdog decided not to apply the rule to platform firms whose annual sales do not exceed 4 trillion won ($2.98 billion) amid concerns that the regulation may end up dampening the growth of the nation's startup ecosystem.

"Monopolistic platform firms are still taking anti-competitive practices by blocking their counterparts from entering the market," the FTC chief told reporters during a briefing.

"The government needs to revise policies to protect the economically disadvantaged, as some platform firms are mired in social controversies, as was shown by the collapse of WeMakePrice and TMON," he said.

The authority will also revise an act on fair transactions in large retail businesses, so big retailers, such as the two now-defunct companies, make timely payments to their sellers.

The FTC is leaving a wide range of regulatory measures open to prevent similar disastrous failures among large platform firms in the future, and will make a final decision by the end of September after reviewing the opinions of experts and the industry.

Under the revised rule, the authority will mandate retail platform firms deposit a certain amount of money that it has received after product sales. The FTC is considering two options: forcing them to set aside either all the sales money or half.

The decision came as WeMakePrice and TMON failed to do so, thereby making delayed payments to their sellers. This ended up with delayed refunds for customers.

"Retail business operators will be obliged to make payments to their sellers on time, and face stricter responsibility in managing money reaped after product sales," Han said. "We will give a certain grace period for platform firms, and gradually strengthen the intensify of the regulation."