During Mr Chavez’s funeral in Caracas on Friday, Mr Ahmadinejad was photographed sympathising with Elena Frias de Chavez, 78.
While it is not a full embrace, the Iranian president and Mr Chavez’s mother have their faces brushed against each other, with their hands clasped in a moment of shared grief. Several news agencies released photos of the unexpected scene.
Muslim men are by tradition forbidden to touch women who are not members of their close family.
Conservative critics, already irked by Mr Ahmadinejad’s effusive eulogy for the leftist leader, reminded him that he has not only committed a sin, but also behaved in a way inappropriate for the president of an Islamic state.
They said it was another sign that Mr Ahmadinejad was influenced by the “deviant current”, a term used to label his close aides, and increasingly himself, and distance him from the Supreme Leader, Ayatollah Ali Khamenei.