Mahiyanganaya police arrested 18 men and two women on Friday morning for various illegal activities.
Two women and eight men were taken into custody when they were at suspicious places, and three were arrested with cannabis.
One illicit liquor seller, four drunken drivers and two illegal sand transporters were among others who were arrested, police said.
Police seized 40g cannabis, one and a half bottles of illegal liquor, six sand cubes and two trucks as well along with the suspects, police said.
They were produced before the Mahiyanganaya Magistrate's Court.