A PCB official said it has been decided not to ask the ICC to have a test of the B sample collected from Yasir after his sample A tested positive for a banned substance leading to the ban.
"Our team of legal and medical experts have advised instead to appeal the suspension on Yasir," the official told PTI.
"We will submit a strong case to the ICC indicating that Yasir took the medicine unintentionally for a high blood pressure ailment and that there was no intention of using banned substances to enhance his performance," he added.
"The idea is to try to get Yasir the minimum suspension period for his mistake so that he can be available to play for Pakistan as soon as possible," one source said.
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PCB's Chairman of the executive committee Najam Sethi also said the Board would not abandon Yasir and support him in his case.
"We will do our best to ensure Yasir gets the best possible help and his career is saved," Sethi said.
More recently, left-arm spinner Abdul Rehman was banned for six months for using a banned substance in English county while last year, young spinner Hasan Reza was also banned for failing a dope test in domestic cricket with traces of cocaine found in his urine samples.
Yasir faces a ban ranging from six months to four years depending on how strong his appeal is.