ICC Chief Executive David Richardson said the CAS decision "vindicated" the world body's bans on the two disgraced Pakistani players.
"The ICC notes and welcomes the decisions of the CAS as they vindicate and confirm the processes and procedures followed by the ICC over the past couple of years in respect of this important, sensitive and high-profile matter," Richardson said in an ICC statement.
Butt's appeal was limited to challenging the sanction only, while Asif challenged both liability and sanction. In both cases, the appeals were dismissed in their entirety.
The ICC said it will now review the detailed judgement before making any further comments.
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The independent anti-corruption tribunal, chaired by Michael Beloff, QC, had found Salman Butt, Mohammad Amir and Mohammad Asif guilty of charges relating to spot-fixing at the Lord's Test match between England and Pakistan in August 2010.
The trio were found guilty at London's Southwark Crown Court in November 2011, on charges of conspiracy to cheat and conspiracy to accept corrupt payments over deliberate no-balls bowled during the Lord's Test. All of them had served prison sentences in England.