He was India captain Rohit Sharma's opening partner in the home T20 series against Afghanistan earlier this year but his place looked under threat as he struggled for runs in the IPL
The 25-year-old took a hat-trick in his first One-Day International against Bangladesh in January, 2018, in Dhaka and played two more Twenty20 internationals on that tour before being sidelined with injuries.
"The decision to suspend will remain intact until a full inquiry is conducted by the SLC into the matter," Sri Lanka Cricket said in a statement.
Madushanka's representatives could not be reached for comment.