A special tribunal of the International Cricket Council opened an appeal hearing on Thursday for the three Pakistan players who face possible life bans if found guilty of spot fixing.

The suspended Salman Butt, Mohammad Amir and Mohammad Asif -who have previously declared their innocence - made no comments as they entered the hearing room in Qatar's capital Doha. But a member of the three-person panel overseeing the proceedings said the credibility of the sport was at stake.

"This is an important hearing for the future of cricket," said Sharad Rao, a former acting attorney general in Kenya, adding that it's critical the sport's image is "very clean where we can rely on the results."

The trio was alleged to have accepted payment for bowling no-balls at prearranged times in a test against England in August at Lord's to fix spot betting markets.

On the closed hearing's first day, which lasted 7½ hours, charges were read and the ÉCC began presenting its evidence including several witnesses.

The ICC refused to provide any details about what evidence was presented, including the identifies of the witnesses. The hearings in Doha could last until next week.