(CNN) -- A brawl broke out in Venezuela's National Assembly on Tuesday as political tensions mounted over disputed elections in the South American country.
Opposition lawmakers claimed they were physically assaulted in a planned ambush by supporters of President Nicolas Maduro's government, while leaders of the United Socialist Party of Venezuela blamed the opposition for instigating violence.
During the fight, government cameras broadcasting the National Assembly session on state television pointed toward the ceiling. Videos sent to CNN en Español and CNN affiliate Globovision by opposition lawmakers show punches being thrown as some try to break up the fight.
The incident comes more than two weeks after authorities announced narrow results in the presidential election to pick Hugo Chavez's successor.
Elections officials have said Maduro won 51% of votes. Opposition candidate Henrique Capriles Radonski and his supporters have called the results illegitimate and vowed to contest them.
The violence among lawmakers comes a day before both sides have planned May Day marches in Venezuela.
On Tuesday, opposition congressman Julio Borges spoke to Globovision with blood dripping on his face.
"I am not the only one who was hit," he said, listing the names of several other opposition lawmakers.
Congresswoman Maria Corina Machado told CNN en Español that she was attacked from behind, hit in the face, thrown to the floor and kicked while.
"It was a premeditated, cowardly, vile, aggression," she said.
"What more has to happen in Venezuela so that the democrats of Latin America and the world react?"
Congresswoman Nora Bracho told CNN en Español that chairs were thrown at the area where opposition lawmakers sit.
The opposition lawmakers, she said, were protesting after they were told they were not allowed to speak if they did not recognize Maduro's election victory. Several of them held up a large banner in protest.
"They denied us the right to speak," she said. "This is an abuse of power."
In a national broadcast several hours later, Maduro decried the violence and suggested that the opposition was responsible.
"What happened today in the National Assembly, we do not agree with violence. They tell us and we knew that the opposition was coming to provoke violence, and there was a strong exchange of blows, very strong. This must not repeat itself," he said, calling for Venezuelans to be peaceful and tolerant.
National Assembly President Diosdado Cabello, Maduro said, "will take measures of authority and discipline so that this does not recur."
Congressman Erick Mago of the United Socialist Party of Venezuela told CNN en Español that the opposition lawmakers' protest Tuesday was aimed at provoking violence.
"We have always called for peace," he said.
Congressman Pedro Carreno also blamed the opposition and said a lawmaker from his party had been injured.
"This uncivilized manner is not how conflicts are addressed in a democracy," he said, according to comments posted on the party's website.
"The right wing, even if they were elected to be lawmakers, cannot use the halls of parliament to spread the winds of war, to attack the peace of the republic, against internal order, against the institutions of the country, and even less to stimulate fascist violence that continues casting a pall over Venezuelan homes," he said.
Journalist Osmary Hernandez reported from Caracas, Venezuela. CNN en Español's Fernando del Rincon and Gabriela Matute Urdaneta contributed to this report.