Geneva - The United Nations human rights chief urged Venezuelan authorities on Tuesday to release anyone detained for exercising basic democratic rights."I am deeply concerned that opposition leaders Leopoldo Lopez and Antonio Ledezma have again been taken into custody by Venezuelan authorities," Zeid Ra'ad Al Hussein said in a statement. "I urge the government to immediately release all those being held for exercising their rights to freedom of peaceful assembly, association and expression."READ: Police take 2 Venezuela opposition leaders from homes Lopez, a Harvard-educated opposition leader, and Caracas mayor Ledezma were taken from their homes at dawn.Venezuela's Supreme Court, which critics say is a mouthpiece for socialist President Nicolas Maduro, said the pair were arrested because of their political statements and that they planned to flee.The court also said the men had violated the terms of their house arrest by engaging in political activities.Lopez was first arrested in 2014 and released to house arrest last month. Ledezma has been under house arrest since 2015.Two previous findings from the UN's independent working group on arbitrary detentions condemned the earlier arrests of both men, saying Maduro's government violated their rights. "I urge the authorities not to make an already extremely volatile situation even worse", Zeid added in his statement, referring to months of crisis in Venezuela, which has intensified due to Maduro's controversial bid to rewrite the constitution. Zeid also condemned weekend violence that reportedly killed 10 people, and warned the authorities against using "excessive force, including through violent house raids by security forces that have occurred in various parts of the country."