Megaupload boss Kim Dotcom on Wednesday offered to voluntarily leave New Zealand for the United States if prosecutors agree to release funds to bankroll his defence against online piracy charges.

The deal would bypass lengthy extradition proceedings under way in New Zealand, which the German national complained were contributing to mounting legal bills he could not pay because all his assets have been frozen.

True to form, the Internet businessman made the proposal on his Twitter feed, which has attracted around 90,000 followers since he began using the micro-blogging website less than a month ago.

"Hey DOJ (Department of Justice), we will go to the US," he tweeted. "No need for extradition. We want bail, funds unfrozen for lawyers and living expenses."

An extradition hearing for Dotcom and his three co-accused, initially set for August 6 in Auckland, was this week pushed back by six months until March next year amid legal wrangling over evidence disclosure.

Dotcom said delays in the case against Megaupload and related file-sharing sites, described by US prosecutors as the world's largest copyright action, were hampering his ability to mount an effective defence.

"I have accumulated millions of dollars in legal bills and I haven't been able to pay a single cent," he told the New Zealand Herald.

"They want to hang me out to dry and wait until there is no support left."

The 38-year-old was sceptical US authorities would accept the proposed deal, which would see him and his co-accused travel to the United States to face charges of money laundering, racketeering, fraud and online copyright theft.

"They will never agree to this and that is because they can't win this case and they know that already," he told the newspaper.

The FBI and Department of Justice allege Megaupload sites netted more than $175 million in criminal proceeds and cost copyright owners more than $500 million by offering pirated copies of movies, TV shows and other content.

Dotcom, who denies any wrongdoing, faces up to 20 years jail if convicted in a US court.

He is currently free on bail after armed New Zealand police, cooperating with the US investigation, arrested him at his sprawling Auckland mansion in January.

New Zealand's High Court last month ruled the raid on Dotcom's mansion was illegal as the search warrants that police used were too broad, further complicating the legal case.

At the same time as the raid, Dotcom's assets were frozen and US authorities shut down the Megaupload sites, which had servers located in the US state of Virginia.

A US indictment alleges that at their peak Megaupload's sites had 50 million daily visitors and accounted for four percent of all Internet traffic.

Dotcom appeared to put forward the possibility of reviving his Internet empire at some point, tweeting: "Mega is looking for reliable non-US based Hosting and Bandwidth providers in Europe, South America and Asia."

"Mega seeks Governments supporting Innovation & Internet Freedom," he added. "The US will lose plenty Internet business. Who wants it?"