The State Department on Friday said it has quietly offered a $10 million reward since January for information leading to those behind the Sept. 11, 2012 attack that killed the U.S. ambassador to Libya and three other Americans in Benghazi.
The men died when militants attacked a loosely guarded U.S. diplomatic compound and a nearby CIA annex in the eastern Libyan city on the anniversary of the 2001 attacks on the United States.
The attacks touched off political warfare on Capitol Hill, with Republicans accusing U.S. President Barack Obama's administration of telling shifting stories about who was behind the attacks. Democrats accuse Republicans of politicizing a tragedy.
The State Department said Secretary of State John Kerry had confirmed that the U.S. government had offered the reward - part of the department's so-called Rewards for Justice program - in a letter to lawmakers on Friday.
Kerry disclosed the reward in a letter to Representative Michael McCaul, a Republican who chairs the House of Representatives Homeland Security Committee and who had written to the secretary of state asking why the State Department had not offered one.
"The State Department today confirmed that since January of 2013 the Rewards for Justice (RFJ) program has had a reward offer of up to $10 million for information leading to the arrest or conviction of any individual involved in the September 11-12, 2012 Benghazi attacks," the department said in its statement.
"Due to security issues and sensitivities surrounding the investigation, the event-specific reward offer has not been publicly advertised on the RFJ website," it added, saying the program can work without advertising rewards on the internet.