WASHINGTON: CIA director Leon Panetta will become US defense secretary and be replaced at the spy agency's helm by US Army General David Petraeus, current head of military operations in Afghanistan, ABC News reported on Wednesday.

President Barack Obama will also nominate veteran diplomat Ryan Crocker as the next US ambassador to Afghanistan, according to an NBC News report.

The positions would require Senate confirmation.

A shuffling of top national security jobs has been an object of speculation for weeks.

Robert Gates, the current Pentagon chief and a former CIA director, had made clear that he planned to step down as defense secretary this year.