The US government has won an appeal in its battle to extradite Megaupload founder Kim Dotcom from New Zealand.

New Zealand’s Court of Appeal ruled that the US authorities need not disclose all of the evidence they have against Dotcom.

Bloomberg quoted a summary of the court’s ruling which said: "If suspects were entitled to extensive disclosure of documents on the basis that they wished to challenge the evidence at the extradition hearing, the procedure would lose much if not most of its efficacy."

Dotcom, who is planning to appeal to the Supreme Court of New Zealand, was arrested together with three others in January 2012, following a raid by police after the US Federal Bureau of Investigation (FBI) had ordered and charged him of internet piracy and breaking copyright laws.

The FBI alleges Megaupload made a profit of $175m since 2005, and had been involved in copying and distributing music, films and other copyrighted content with no authorisation.

Last year, US District Judge Liam O’Grady turned down Dotcom’s appeal to dismiss copyright infringement charges against the file-sharing site.

Megaupload operated sites that include Megavideo.com and Megapix.com. It claimed to receive 50 million daily visitors which accounted for a whopping 4% of all Internet traffic.