US Defense Secretary Leon Panetta said Thursday he was "not aware" of any other officials linked to the sex scandal that brought down CIA chief David Petraeus and embroiled another top general.

"I am not aware of any others that could be involved in this issue at the present time," Panetta told reporters in Bangkok after talks with his Thai counterpart.

Petraeus, the most celebrated US general of his generation, credited with turning around the war in Iraq, resigned last week to pre-empt revelations of an affair with biographer Paula Broadwell, a married army reservist.

The US commander in Afghanistan, General John Allen, has also been linked to a key figure in the case and is now under investigation for potentially inappropriate emails.