Salman Butt is one of three Pakistan cricketers accused of fixing spot betting markets. ((Emmanuel Dunand/Getty Images))

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 ICC 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.

After the first day, the youngest of the trio, 18-year-old fast bowler Amir, admitted to the cricinfo website that the recent months have been "tough" for him.

"This is a question of my career and I've been through some tough days," he told the website. "I've overcome them and I will, hopefully, overcome more in the future.

"We've prepared well for the case and put in our effort."

Amir's lawyer Shahid Karim hinted he may try to use the player's youth to argue for leniency should he be found guilty.

"If you look at the ICC code, there could be some advantage with that," Karim said. "He is very important to the future of Pakistan.

"And the response we have gotten from people so far, I am very hopeful. You can call our case strong or whatever, but I am hopeful."

The Dubai-based ICC, which has described the allegations as the sport's biggest fixing scandal in decades, charged the trio with corruption in September after a British tabloid, the News of the World, alleged the players received payments from businessman Mazhar Majeed.

Majeed, who was also arrested and questioned by police, appeared to accept 150,000 pounds ($241,000 US) from reporters posing as frontmen for a Far East gambling cartel.

The ICC on Sept. 2 charged the players with various offences under its anti-corruption code relating to "alleged irregular behaviour" during the fourth test against England — charges that could lead to life bans.

Pakistan, meanwhile, is scheduled to open a two-test series on Friday in New Zealand. Pakistan recently drew a two-test series 0-0 with No. 2-ranked South Africa.