Haskell, who has signed with the Highlanders for the 2012 Super 15 season, and England team-mate Chris Ashton were fined by the English Rugby Football Union (RFU) after it was alleged the pair harassed hotel worker Annabel Newton while they were staying at the Southern Cross Hotel.
The players accepted they made an inappropriate joke but have denied any serious wrongdoing.
The story took a further twist at the weekend with reports in the United Kingdom suggesting the pair had been advised by the RFU to buy Newton's silence with a payment of $30,000.
However they have refused to pay the money, and are reportedly furious with the way they have been treated by their union.
The Daily Telegraph reports Haskell's legal representatives have now sent a letter to Ms Newton demanding that she withdraws her allegations and confirms the incident on Sept 9 was no more than "light-hearted banter between herself and the players''.
The deadline for the retraction expired on Saturday, and Haskell's legal representatives have warned they "will take the appropriate steps to clear his name and to recover his financial loss'', the Telegraph reported.
The lawyer for the rugby player also said a video of the incident, recorded by teammate Dylan Hartley, will confirm Haskell's story.
