A US judge has ordered a company to preserve data on the servers of file-sharing website Megaupload while negotiations continue over who should pay to keep it accessible.

At a hearing in Alexandria, Virginia, District Judge Liam O'Grady deferred a decision on the fate of millions of gigabytes of data uploaded to the servers by up to 60 million Megaupload users.

The files have been inaccessible since the website was taken offline in January.

Server company Carpathia Hosting says it is costing $US37,000 ($NZ44,900) per month to keep the data and it can't continue paying, DPA reports.

It had agreed to sell the servers to Megaupload for $US1.2 million.

Lawyers for Megaupload say the data is necessary as part of their defence.

But the sale was rejected by lawyers for the US Department of Justice and the Motion Picture Association of America.

"It's like trusting the thief with the money," prosecutor Jay Prabhu told the court.

Mr Prabhu said the government was not seeking the data's erasure but it was also not the government's responsibility to maintain the files, the Associated Press reports.

The Motion Picture Association says the files include the largest-ever collection of copyright-infringing material.

Other parties in the case include an Ohio man who says he used the website for legitimate purposes, and was seeking access to his data, Bloomberg reports.

Julie Samuels, an attorney for internet civil liberties group Electronic Frontier Foundation, argued that the government should establish a system so the website's users can file claims to their data.

Judge O'Grady deferred his decision for two weeks to allow the parties to meet and reach an agreement on who will take responsibility for the servers.

Megaupload founder Kim Dotcom and three others are on bail in New Zealand awaiting a hearing - planned for August - to extradite them to the US, where they face charges of copyright infringement, money laundering and racketeering in relation to the popular file-sharing website.

The group were arrested in January following a raid on Dotcom's Coatesville mansion, with the case so far costing New Zealand taxpayers more than $1m.