After a former South Korean air force chief was indicted on charges of leaking military secrets to Lockheed Martin, the U.S. defense firm Thursday denied any illicit activity on its side.

South Korea's state prosecutors announced earlier this week that the ex-airman, identified only by his family name, Kim, and two other former air force officers were charged with handing over classified information on South Korea's weapons purchases and development in return for US$2.3 million in commission fees from the company in 2009 and 2010.

The three were running a weapons contract brokering agency after retirement, according to the Seoul Supreme Prosecutors' Office.

"The firm in question was retained to provide business consulting services to Lockheed Martin in Korea," said Tom Casey, director of international communications at Lockheed-Martin headquarters in Bethesda, Md.

"Our agreement with the firm in question and all of our representatives and consultants expressly prohibits them from providing us with such information," he added by email. "Our policy is that we do not accept or solicit such information, and we prohibit our consultants and representatives from providing us such information."

He said Lockheed Martin has fully cooperated with investigation by South Korean prosecutors. (Yonhap News)