The founder of a popular file-sharing site is taking extreme legal action against the New Zealand government, and hoping to fill his pockets with billions in the process.

An arrest warrant has been issued by the US government for Kim Dotcom, the founder of Megaupload. Dotcom (born Schmitz) is facing charges of fraud and copyright infringement. The US is demanding he be extradited from New Zealand.

It is alleging that Megaupload allowed pirated files to be stored online. Dotcom refused to remove the content and said it was the responsibility of the file uploader holders to delete the files. The US claims film and record companies lost £322m in potential sales as a result.

Dotcom was arrested in 2012 during a raid and Megaupload was shut down. According to the BBC, Dotcom's accountants estimate the business would be worth $10bn today. Dotcom owned 68% of the company and is suing for $6.8bn in damages.

"I cannot be expected to accept all the losses to myself and my family as a result of the action of the New Zealand government," Dotcom told the BBC. "This should never have happened and they should have known better. And because they made a malicious mistake, there is now a damage case to be answered."

"Under the NZ copyright act, online copyright infringement is not a crime," he said. "In order for the US to be successful with an extradition, the allegation of the crimes that they are charging someone with also have to be a crime in the country from which they request extradition."

Dotcom will be at the Appeals Court on 20 February as his extradition case continues.

On 16 January, Dotcom was given two containers of assets that been held by the Hong Kong government. "It's about $2m worth of designer furniture and high-tech stuff," he said, according to the BBC. "But most frustrating is the loss of our family archive of 800 hours of video, the birth of my children, birthdays, holidays - it's really sad."

Dotcom married his partner Elizabeth Donnelly on Saturday (20 January) in Auckland. He lives on New Zealand's south island in Queenstown.