The PHU leader, Udaya Gammanpila filed a petition in the Supreme Court on Friday against the proposed 20th Amendment to the constitution.
Mr Gammanpila said the Amendment should only be passed following a public referendum.
"The Constitution clearly says a referendum should be held if presidential elections or the general election is being postponed. Though it doesn’t mention about the provincial council elections, people practice their franchise through elections. Therefore, the Constitution says any amendment related to people's franchise should receive the consent of the people at a referendum," he was quoted by the Daily Mirror as saying.