Sri Lanka Cricket took the decision after Madushanka was arrested and later sent on remand custody for alleged possession of illegal drugs.
Madushanka was in possession of a little over two grams of heroin when arrested on Saturday, Sri Lanka Police's media division had confirmed to ESPNcricinfo.
As per an SLC release, the decision to suspend will remain intact until SLC conducts a full inquiry of the matter.
Madushanka had been arrested for the possession of heroin and remanded by a local magistrate in Pannala, northeast of the city of Negombo.
The cricketer has not appeared for Sri Lanka in the last two years and has not been in the frame for selection recently.
He is, however, an active cricketer and was playing in Sri Lanka's domestic competitions before the Covid-19 curfews came into effect.
The player had been in possession of a little over two grams of heroin when arrested on Saturday, Sri Lanka Police's media division confirmed to ESPNcricinfo.
He was then produced before a magistrate on Sunday, and is currently in remand, awaiting a High Court appearance.
He is not understood to be among the players required to begin training in June with the national squad.
Sri Lanka Cricket CEO Ashley de Silva said the board had been made aware of the arrest on Monday morning, but had not made any decisions on the player's future.The board is expected to discuss the issue at their next meeting, on Wednesday. AGENCIES