The UNP Working Committee has expelled 54 members who are contesting the election under the Samagi Jana Balawegaya (SJB).
The UNP has also expelled 61 Local Government members who have failed to support the party's election campaign.
The UNP previously warned that stern action would be taken against those supporting the Samagi Jana Balawegaya led by Sajith Premadasa.
The move comes nearly a week ahead of the Parliamentary eleciton.