UN Secretary General Antonio Guterres on Tuesday urged Venezuela's authorities to make "all possible efforts" to ease tensions and prevent further violence after two opposition leaders were sent back to prison.
Guterres "has taken note" of the decision to revoke the house arrest for Leopoldo Lopez and Caracas mayor Antonio Ledezma who were returned to jail, said UN spokesman Stephane Dujarric.
"In this critical moment for the future of the country, the secretary-general urges all Venezuelans, particularly those representing the powers of the state, to make all possible efforts to lower tensions, prevent further violence and loss of life, as well as find avenues for political dialogue," he added.
Venezuela's Supreme Court said in a statement that Lopez and Ledezma had violated the terms of their house arrest and that they had a plan to flee the country, claims that lawyers representing the pair denied.
The decision came before a new assembly elected on Sunday is due to take office with the task of rewriting the constitution, a plan that the opposition maintains will allow a slide toward authoritarianism.
The UN chief renewed his appeal for urgent political talks and said he supports regional mediation efforts along with those of international facilitators.
Venezuela has been rocked by street protests against President Nicolas Maduro's rule that have left 120 dead since April and raised international alarm that the country may be headed toward all-out conflict.