The International Cricket Council anti-corruption group are looking into widespread allegations of match-fixing, with 12 players said to be under investigation.
According to the Daily Mail, McCullum told investigators that a player offered him £107,000 in a Worcester cafe during New Zealand's tour in 2008 to purposefully play poorly.
McCullum reportedly said in his evidence that the player in question told him to buy property in Dubai through an employee of the ICC in order to hide the corrupted money.
It has also been reported that the player told McCullum that all the "big boys" in international cricket were involved in fixing matches.
The newspaper has also revealed that McCullum was first approached in Kolkata in 2008 before the start of the Indian Premier League.