South Korea's antitrust watchdog said Tuesday it has slapped a combined 1.54 billion won ($1.3 million) fine on six conglomerates for breaking regulatory filing rules as the country moves to better protect the rights of shareholders.

The action by the Fair Trade Commission comes after a three-year probe that kicked off in April 2012, which checked the practices of the country's largest business groups.

The FTC said 28 affiliates belonging to six conglomerates failed to complete or delayed filings related to large scale intra-group transactions that must be reported to all shareholders.

Some companies have been found to have skipped the voting process with their boards of directors.

Under South Korean law, companies belonging to conglomerates barred from cross-unit investments must report all deals with other affiliates if the sum exceeds 5 billion won. This cover flows of funds, assets and stocks as well as trading in goods and services.

The six business groups are OCI, Dongbu, Kumho Asiana, Hyosung, Daelim and Young Poong.

"Companies penalized were found to have not made regulatory filings, or delayed the mandatory process," the FTC said. "Others failed to go through the proper voting procedures by their respective boards."

Among the offenders, chemical company OCI has been slapped with a 992 million won fine and Dongbu must pay 293 million won.

The corporate regulator said its latest move will get companies to follow rules designed to keep stockholders informed and enhance overall corporate transparency. It said authorities will continue to check if companies adhere to regulatory filing rules in the future. (Yonhap)