The claim, if shown to be true, could explain why William Hague, the Foreign Secretary, said on Monday that he had reason to believe Col. Gaddafi himself was heading to Venezuela as protests against his regime threatened to topple him from power.

“The caller to the Venezuelan Foreign Ministry was Gaddafi’s son and not Gaddafi,” said Mr Medina, a former governor of the state of Lara in northwestern Venezuela.

He challenged the government of Hugo Chavez, who has enjoyed warm relations with Col. Gaddafi and has a football stadium in Libya named after him, to deny his allegation.