The International Cricket Council (ICC) provisionally suspended the 25-year-old after he failed an out-of-competition anti-doping test in October.
Sri Lanka Cricket sent back Perera from their tour of New Zealand earlier this month while also promising to provide support for the dashing left-handed batsman to get back on the field as soon as possible.
"The ICC has informed that his B sample also has been tested positive for a banned drug," Sri Lanka sports minister Dayasiri Jayasekera told reporters on Friday.
"We are appealing against this because he was never found like this in the last four instances.
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"We will back him with legal representation while doing every possible effort to help him to get out of this issue."
The cricketer faces a maximum ban of four years according to the ICC's anti-doing code.
(Reporting by Shihar Aneez, writing b Sudipto Ganguly, editing by Pritha Sarkar)
