The Crown says it will appeal against a decision to grant bail for Megaupload founder Kim Dotcom.
The United States government is seeking the extradition of Mr Dotcom and three other men. They face charges in relation to the file-sharing website, including copyright infringement and wire fraud.
Mr Dotcom, a German millionaire who has New Zealand residency, was arrested at his leased mansion near Auckland on 20 January in connection with a major internet piracy prosecution and has been in custody.
The 38-year-old was freed on bail on Wednesday after a North Shore District judge ruled that he was no longer a flight risk.
The Crown is expected to argue that Mr Dotcom should be returned to custody at a court hearing on Tuesday.
An extradition hearing for all four men on bail in New Zealand is set down for August this year.
US authorities allege that Megaupload has profited by at least $175 million and want to seize more than 60 of its bank accounts.
Authorities have until 5 March to file extradition papers.