Two former conservative Latin American presidents were blocked from visiting jailed opposition leader Leopoldo Lopez on Sunday.

Former Colombian President Andres Pastrana and Former Chilean President Sebastian Pinera, both of whom have been allies with the United States, traveled to the capital city of Caracas this weekend to participate in a pro-democracy march organized by President Nicolas Maduro's opponents, Reuters reports. Thousands of Venezuelans attended the demonstration, banging empty pots in protests of food shortage and calling for Maduro to step down.

"Leopoldo Lopez is a politician, one can disagree with his ideas but that does not provide the right to deprive him of his freedom," Pinera said at the entrance to the Ramo Verde military prison.

As part of their visit, the two conservative leaders endeavored to visit with Lopez, who is in a military prison where he has been held for the past 11 months Lopez is accused of instigating violence in anti-government protests last year that, according to the government, led to the deaths of some 43 people. On Feb. 18, before a crowd of thousands, and amid much cheering and weeping, López turned himself in to the Guardia Nacional.

After being informed by the prison guards that their entrance would not be allowed, Pastrana declared that Lopez's basic human right to receive visits from friends and family was in fact being denied.

Lopez is charged with instigating crime and with being the intellectual author of public damages as well as arson in connection with three months of anti-government protests that began last February.

On Friday, Maduro linked the former presidents' visit to a right wing conspiracy meant to destabilize his government. He sees Lopez as a criminal who has masterminded months of protests and has dismissed all calls for his release. According to Associated Press , Maduro said on Friday that the former presidents had "blood on their hands."

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