The variation in the quantity of nandrolone found in Asif's two samples may have been caused by testing procedures.

This was hinted by Dr Ravi Bapat, a member of the three-man Indian Premier League drugs panel that will hear the Pakistan bowler's appeal against a positive doping test.

Asif tested positive for the banned drug during the semi-finals of the IPL in May and a `B` test at a WADA-accredited laboratory in Lausanne, Switzerland, last week returned a similar result.

However, while his first sample displayed a reading of 6.2 mg, the second test showed only 5.4 mg of the drug.

Asif's fate will be decided by an IPL drugs tribunal comprised of former Indian Test skipper Sunil Gavaskar and lawyer Shirish Gupte as well as Bapat.

The 25-year-old has indicated that the difference in the results will form the basis of his appeal and Bapat conceded it could be down to the way they were processed.

"It may not be common but there are several reasons for the discrepancy," Bapat told reporters.

"We have to study the method of collection, the way the samples were stored and the mode by which the samples were transported to the laboratory in Switzerland.

"We are yet to receive the official report on the case but I've already started work on the case."

Asif could be banned for a minimum of two years by the tribunal.

Bapat, however, insisted no date had yet been set for the hearing.

"It's up to Asif to appeal," he said.

"We can only assure him of a fair hearing."