Venezuela's opposition-controlled congress has returned to its chambers a day after security forces prevented its members from entering the National Assembly building for a debate.

Opposition leader Juan Guaidó and other legislators on Wednesday gave speeches denouncing the government of President Nicolás Maduro, who has accused them of conspiring with the United States to stage a coup.

The National Assembly has come under increasing pressure from Maduro since the opposition appealed in vain for a military uprising on April 30. The assembly's vice president, Edgar Zambrano, was arrested May 8. He is among 14 lawmakers placed under investigation for alleged treason and other crimes since the failed rebellion.

On Tuesday, police sealed off the National Assembly, purportedly to search for any hidden explosives.