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.
But on Thursday night the website of the Venezuelan government continue to prominently show a statement highlighting the "irresponsible comments" of Mr Hague without addressing the whereabouts of Col. Gaddafi's sons.
The Libyan leader has seven sons including Saif al-Islam, who has a PhD from the London School of Economics and recently appeared on television to warn of a possible civil war, and Mutassim, who is Libya's National Security Adviser.
Mr Medina said it had not been disclosed to him which of the dictator's sons had flown into exile.
A columnist in one Venezuelan newspaper, El Universal, claimed that there was intelligence to suggest that one of Gaddafi's wives and four of her daughters were also now on Margarita Island.
Margarita Island is well known to Col. Gaddafi as he attended a summit for South American and African leaders there in 2009, even going on a surprise shopping trip with his entourage and posing for photographs with shop staff.
