The MP's son and his friends had been enjoying themselves at a restaurant in Boralesgamuwa when they had gotten into an argument with a businessman from Maharagama and his wife.
After the couple had left, Wedaarachchi's son and his friends had followed them, blocked their way and assaulted the businessman.
Policemen in the area have intervened, and arrested the assaulters.
MP Wedaarachchi too, had subsequently arrived and the businessman had told the group that in order to end the matter there and then, he should be compensated for the damage to his watch, which is Rs. 1.5 million in value.
He had asked for Rs. 1.2 million as compensation, but both parties have agreed at Rs. one million and to settle the matter, police sources say.