“Welcome to liberty!” Andrés Pastrana, a former president of Colombia, said on Twitter. “We need you free in the world, defending liberty, human rights and democracy and not a prisoner by the narco-dictatorship of @NicolasMaduro.”
Mr. Ledezma was arrested in February 2015 while serving as the mayor of Caracas, on accusations that he had plotted with the United States to topple Mr. Maduro’s government. He and the United States denied the charges and Mr. Ledezma’s allies saw the detention as an attempt by Mr. Maduro to weaken the opposition ahead of legislative elections later in the year.
Until his escape on Friday morning, Mr. Ledezma had been held under house arrest without trial since 2016, except for a brief interim imprisonment following a dramatic late-night raid on his house in August.
It remained unclear how he managed to escape on Friday, but the Colombian government said he crossed the border by way of the Simón Bolívar International Bridge, which connects the Venezuelan city of San Antonio del Táchira with the Colombian town of Villa Rosario.
Relations between the two countries have been very tense. Earlier this year, Colombia’s president, Juan Manuel Santos, recalled his ambassador to Caracas and labeled the Maduro administration a dictatorship.
Mr. Maduro’s jailing of his opponents has been widely criticized by foreign governments and democracy advocates worldwide, and the Trump administration used it as a justification for imposing sanctions this year against Mr. Maduro and dozens of officials in his government.
Alfredo Romero, head of Foro Penal, a human rights group in Venezuela, said on Friday that when Mr. Maduro took office in 2013, there were only 11 jailed opposition activists — he called them “political prisoners.” That number rose to 676 in August, at the height of the anti-government protests earlier this year, he said.
Following the election of the new, all-powerful legislative body, the Constituent Assembly, Mr. Maduro started releasing opponents from prison. As of Friday, Mr. Romero said, the number of jailed activists stands at 342.
Early this month, the Maduro administration released two other prominent activists that had been held without trial for more than a year, Yon Goicoechea and Delson Guarate.
At about the same time, however, Freddy Guevara, another prominent opposition figure, sought asylum in the Chilean Embassy in Caracas after the Supreme Court blocked him from leaving the country and the Constituent Assembly stripped him of his political immunity from prosecution on suspicions of instigating unrest during this year’s protests.