The United States State Department said it had since January been offering financial rewards of up to $10 million for information that leads to the arrest or conviction of anyone who took part in attack on the US diplomatic compound in Libya last year.
The State Department said it had not publicly announced its the bounty on its "Rewards for Justice" website - as is usually done - due to "security issues" connected to the search for those responsible for killing US Ambassador to Libya Chris Stevens and three other Americans on Sept. 11, 2013.
"Due to security issues and sensitivities surrounding the investigation, the event-specific reward offer has not been publicly advertised on the RFJ website," the department said in a statement. "RFJ tools can be utilized in a variety of ways, without publicizing them on the website."
According to the Associated Press, the State Department had been reluctant to discuss the bounty program.
In August, the US filed charges against Libyan militia chief Ahmed Abu Khattala and other alleged attackers.