In a decision issued on Monday, the New Zealand High Court upheld a 2015 district court ruling against Kim Dotcom, maintaining that he was eligible for extradition.

The United States has been seeking to have Dotcom and three of his former colleagues - Mathias Ortmann, Bram van der Kolk and Finn Batato - sent for trial on 13 counts including conspiracy to commit racketeering, copyright infringement, money laundering and wire fraud since 2012.

The charges relate to the operations of Megaupload, a file sharing website founded by Dotcom. US prosecutors allege Megaupload netted some $175 million in criminal proceeds and cost copyright owners about $500 million by facilitating internet piracy.

Dotcom argues he can't be held responsible for the actions of Megaupload's millions of users. He and his co-accused could face decades in jail if found guilty in the US.

"Look, we're disappointed it's not all over in the [New Zealand] high court," Dotcom's lawyer Ron Mansfield said. "But we're one step away, as far as we're concerned, from winning outright," he added, indicating the case would be taken to the Supreme Court if necessary.

The High Court agreed with part of Dotcom's appeal - that copyright infringement was not an offense which warranted extradition. However the judge ruled there was enough evidence to put Dotcom on trial for criminal fraud, meaning he could be sent to the US.

"We won but we lost anyway," was how Dotcom summed it up to his followers on Twitter, of which he is a frequent user.

Dotcom was arrested five years ago following a dramatic raid on his mansion near Auckland which was requested by US authorities. The German citizen, born Kim Schmitz, had gained residency in New Zealand under an investment scheme which benefits the wealthy.

During his time on bail he released a music album, created another file sharing company and launched a political party which failed to win a place in parliament during New Zealand's 2014 general election.

se/rc (AFP, AP, dpa)