Secretary of State Hillary Clinton will appear before lawmakers on January 23 to be quizzed about the deadly attack on a US mission in Libya, just days before she steps aside as top US diplomat.

The chairman of the House Foreign Affairs Committee, Ed Royce, announced the date in a statement late Monday. A Republican senator last week said Clinton likely would make her appearance before Congress January 22.

"My intention is for this hearing to focus on why this attack was not better anticipated, what leadership failures at the State Department existed, and what management deficiencies need to be corrected in order to better secure our diplomatic facilities abroad and protect our diplomats serving in them," wrote Royce, a California Republican.

"It is important to learn all we can about what happened in Benghazi because at the end of the day, it could happen again," he added. "After all, Al-Qaeda plans attacks over and over again."

Clinton was to have testified December 20 after a scathing inquiry blamed "grossly inadequate" security at the diplomatic outpost in Benghazi for failing to protect staff there.

But she was forced to cancel her testimony and send in her two deputy secretaries instead when she fell ill with a virulent stomach bug and later suffered a concussion and blood clot.

Ambassador Chris Stevens and three other Americans were killed when heavily-armed militants overran the compound and a nearby annex on September 11 in a bloody and terrifying eight-hour assault.

The Accountability Review Board set up by Clinton to investigate the attack found "systemic failures and leadership and management deficiencies at senior levels within two bureaus of the State Department" responsible for security.

Assistant Secretary Eric Boswell, head of the bureau of diplomatic security, resigned his post after the report was released and was placed on administrative leave along with three other senior staff.

President Barack Obama has tapped the veteran Democratic senator John Kerry to replace Clinton, but his nomination requires confirmation by the Senate, which is in recess until January 21.