Butt and teammates Mohammad Amir and Mohammad Asif were jailed and banned for a minimum of five years in 2010 by the International Cricket Council for spot-fixing -- in this case bowling deliberate no-balls -- during a test match against England. Butt was captain for the match.
While Amir pleaded guilty and didn't contest the punishment, Butt and Asif saw their appeals rejected by the Court of Arbitration for Sport last year. The minimum five-year bans for all three players are due to end in Sept. 2015.
Sethi said top lawyers in UK have advised him that Butt and Asif do not have strong cases.
"I wish what he (Sethi) is doing for Amir, he should also do for other (banned) players too," Butt told reporters in Lahore.
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"Pakistan does need Amir and I wish him all the best, but I think other players should also get similar treatment."
It's not yet clear how the banned players would return to international cricket once the anti-corruption laws are amended. However, Sethi said he had strongly pleaded Amir's case at the board meeting in Dubai earlier this week, noting that Amir pleaded guilty and also underwent rehabilitation.
"I have met with PCB's anti-corruption official at least 10 times, but he always says that the board will let me know," said Butt, adding that "people do make mistakes, but once they serve their punishments they should be given a chance to revive their lives.