A number of left-wing deputies exchanged blows with conservative officials when the former tried to take the podium to denounce the upcoming inauguration of President-elect Felipe Calderon.
The protesting lawmakers said the Calderon election was a fraud.
The president-elect defeated Andres Manuel Lopez Obrador by less than 1 percentage point, according to exit polls.
Earlier this month Obrador declared himself the country's alternative president of a parallel government following his own inauguration ceremony.
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