Lawmakers in Venezuela's opposition-controlled congress said their chamber was stormed by officials from a rival assembly loyal to President Nicolas Maduro with the backing of soldiers.
The legislature posted photos on its Twitter account of a group of people in the chamber it uses in the Legislative Palace in Caracas.
It shares the building with the "Constituent Assembly," a body Maduro created through an election just over a week ago that the opposition boycotted and denounced as illegitimate.
The people who invaded its chamber, it said, included the leader of the Constituent Assembly, Maduro's former foreign minister Delcy Rodriguez.
The lawmakers have been fearing that the Constituent Assembly, which has been given supreme powers over all branches of government, could dissolve the congress as a way of consolidating Maduro's power.
On the weekend, the new assembly fired the country's attorney general, Luisa Ortega, who had been an outspoken critic of Maduro's.
The incident followed one on July 5 in which violent supporters of the government burst into the legislature and wounded seven opposition lawmakers.