It is for this very reason that the opening batsman was omitted from Sri Lanka's squad for the ODI series against Pakistan in the UAE.
The official SLC release further stated that Gunathilaka pleaded guilty to the charges on September 29.
The 26-year-old is reported to have skipped a training session after late night partying.
In a separate incident he had turned up at the ground during a match day without his kit bag during the India series.
Gunathilaka made his Test debut against India in Galle in July. He played the first two ODIs as well but a shoulder injury ruled him out of the remainder of the series. (ANI)