The ICC insists it's substantially revamped its anti-corruption arm since Brendon McCullum's reporting of match-fixing.
The former Black Caps captain lambasted the governing body in his Cowdrey Lecture speech at Lord's yesterday.
He was furious his statement about Chris Cairns to the ICC was leaked to the media and was scathing of the ICC's evidence-gathering process.
In a statement, the ICC has commended McCullum for his brave stand against corruption in cricket but is adamant it was not the source of the leak.
"The ICC commended Brendon McCullum two years ago - and continues to do so today - for his brave, courageous and principled stand against corruption in cricket," the ICC said in a statement.
"The ICC also understood and shared his dismay at the leak of his confidential statement, which prompted a thorough and detailed investigation by the ICC. While the probe proved that the origin of the leak was not from within the ICC, it failed to establish beyond doubt the actual source.
Nevertheless, the ICC has already put strong measures in place to ensure this type of incident is never repeated.
"In 2014 (and unrelated to the leak of confidential information), a comprehensive review of the ICC Anti-Corruption Unit was carried out to review its processes, functions and resources. The review was conducted by the ICC's Integrity Working Party (IWP), which included independent corruption experts. All the recommendations of the IWP were reviewed and adopted by the ICC Board during the 2015 ICC Annual Conference in Barbados.
"Every event or incident provides an organisation with opportunities to review its structures and measure its operations against best practice. This is exactly what the ICC has done in this particular case - it believes the outcome has been processes, procedures and resources which have been further bolstered and strengthened."
The England and Wales Cricket Board declined to comment in response to McCullum's criticism of its treatment of Lou Vincent.