Twenty one party activists were injured allegedly by police while demonstrating against the bill that will address the demands of the agitating Madhesi parties and other ethnic groups.
The opposition parties have been opposing the bill registered in the Parliament that aims to divide parts of the Province No 5 and merge them into the Terai region bordering India.
Meanwhile, CPN-UML issued a statement asking the government to immediately release its party workers arrested during the demonstration.
Speaker Onsari Gharti had then postponed the Parliament meeting until 3 PM today.
Nepal has been facing political crisis since the adoption of a new Constitution in September last year that divides the country into seven provinces.
The agitating Madhesi parties want the hilly districts not to be mixed with the plains while demarcating the provincial boundaries.