SEOUL (Reuters) - South Korea's market watchdog has decided to impose fines on JPMorgan ( JPM ), Morgan Stanley ( MS ), Nomura and UBS for violating short-selling rules in the domestic stock market, officials at the country's Financial Supervisory Service (FSS) said on Thursday.

"We have concluded administrative sanctions, meaning imposing fines," an official said, declining to provide further details because the decision had not been officially disclosed.

The decision was made on Wednesday by the Securities and Futures Commission, according to another official at the FSS.

Nomura said it was not aware of any decision by the regulator and could not comment. JPMorgan ( JPM ) and Morgan Stanley ( MS ) declined to comment, while UBS said it did not have any comment at this time.

In South Korea, naked short-selling of stocks, or selling stocks without borrowing them first or determining they can be borrowed, is banned by the Capital Markets Act.

South Korea plans to lift in March a market-wide ban introduced in November 2023 on stock short-selling, when it is expected to have a system ready to detect illegal trades.