Venezuela has freed Juan Pablo Guanipa, a political ally of opposition leader Maria Corina Machado, after eight months in detention, his son has said.

The former vice-president of the National Assembly is among several political prisoners to have been released since the US captured Venezuela's President Nicolas Maduro in January.

"Our entire family will be able to hug again soon," Ramón Guanipa wrote on social media, cautioning: "There are still hundreds of Venezuelans unjustly imprisoned."

Opposition and human rights groups say the government under Maduro had for years used detentions of political prisoners to stamp out dissent and silence critics.

Though the interim government instituted in his absence promised on 8 January that "a significant number" of detainees would be released, this has progressed slowly in the weeks since, with a handful being released at a time.