Samarawickrama said that he has tendered his resignation letter to UNP leader, Prime Minister Ranil Wickremesinghe.
The move is part of reforms taking place in the UNP.
Last week UNP General Secretary Kabir Hashim had resigned from his post in the party to make way for reforms in the UNP.
There is speculation that former Minister Imthiaz Bakeer Markar will be offered the post. (Colombo Gazette)