The United Nations human rights chief said Tuesday he was "deeply concerned" by the re-arrest of two Venezuelan opposition leaders, urging Caracas 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," the UN High Commissioner for Human Rights, 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."