Image caption Kim Dotcom has been denied bail in New Zealand and is fighting extradition to the US

US prosecutors have added wire fraud and additional criminal copyright infringement counts to their case against file-sharing site Megaupload.

New details have emerged as officials filed a 90-page superceding indictment against the company and its founder Kim Dotcom.

The site is accused of costing copyright holders more than $500m (£320m) in lost revenue.

The company says it was diligent in responding to pirated material.

In the indictment, the Department of Justice alleges that Megaupload organised the company's computer system's architecture around the "rapid and repeated distribution" of copyrighted works.

The company allegedly reproduced materials from other websites, including YouTube, and made them available on Megaupload.

User 'VV'

The new wire fraud charges are based on communications from the company to copyright holders.

In those emails, defendants falsely represented that infringing content had been removed when it had not been removed, Justice Department officials say.

The document also highlights one account holder that uploaded 16,950 files to sites the company owned, generating more than 34 million page views over the course of six years.

User "VV" was subject to numerous requests for removal, but records show no deletions of any of VV's uploaded files.

Megaupload paid user VV $3,400 through its rewards programme over the course of two years.

The indictment also contends that the site did not have have as many registered users as they claimed, and that of the 66 million registered accounts, only 5.4 million had ever uploaded a file to the service.

The Department of Justice has also added various properties, jet skis and jewellery to the list of assets subject to forfeiture.

Earlier this month, Mr Dotcom was denied bail in New Zealand.

He has denied the charges and has said he would fight an extradition application by the US.