Nearly 20 backbenchers representing the UNP have decided to boycott meetings attended by Prime Minister Ranil Wickremesinghe.
MP Hirunika Premachandra said the decision was made in protest of the manner in which internal reforms of the party were carried out.
She said Prime Minister Wickremesinghe should step down from the UNP leadership and allow the party's decision making bodies to elect the new party officials.
She also added that the current UNP constitution must change in a manner that safeguards democracy within the party.
However, she stated that Prime Minister Wickremesinghe should not step down from the premiership.