Venezuelan President Nicolas Maduro's administration has blockaded the congress building.
The government sent police units to enforce the blockade on Tuesday. It cited the possible presence of an explosive device inside the building.
Opposition leader Juan Guaido says the government is trying to seize the congress, where the opposition has a majority. He urged lawmakers to keep on entering the building and is calling on military personnel to join anti-government rallies.
Guaido declared himself interim president in January. Early in May, he urged the military to rise up against the government. But the coup attempt failed, and Maduro has been arresting lawmakers and military officers who support Guaido.
No solution appears to be in sight to the standoff between Maduro, who is supported by Russia and China, and Guaido, who is backed by the United States.