TOKYO, Dec 15 (Reuters) - An investigation panel recommended on Friday administrative action against Japan's largest online securities broker, SBI Securities, saying it had accepted buy orders meant to inflate companies' share prices after initial public offerings (IPOs).

Japanese law bars the acceptance of buy or sell orders intended to manipulate a company's share price.

The Securities and Exchange Surveillance Committee (SESC) made its recommendation to Japan's regulator, the Financial Services Agency (FSA), saying the firm aimed to boost opening prices of three stocks for which it served as lead underwriter.

SBI Securities took the recommendation very seriously and would work to make improvements and prevent a recurrence, it said in a statement.

Japanese media first reported the result of the panel's investigation on Wednesday, while SBI said at the time it did not recognise the reports. (Reporting by Anton Bridge; Editing by Clarence Fernandez)