US authorities shut down Megaupload last year, accusing Mr Dotcom of helping people share movies and music illegally. A huge amount of Megaupload data has been deleted by a European hosting firm.

Kim Dotcom called it the "largest data massacre in the history of the internet," saying that millions of users' personal files had been lost, petabytes of data.

Dutch firm LeaseWeb said that it needed to "reprovision the servers". It said that it had maintained the 630 servers at its own expense since Megaupload was shut down in January 2012, following raids led by the US authorities. "After a year of nobody showing any interest in the servers and the data we considered our options... we commenced the re-provisioning of the servers in February 2013".

On Twitter, Mr Dotcom said that his lawyers "had repeatedly asked LeaseWeb not to delete Megaupload servers while court proceedings are pending in the US". He claimed he was never warned about the deletion, adding that the loss of the files had reduced him to tears.

The deleted servers represent only a small fraction of those leased by Megaupload, to provide storage space for users. In North America alone, the firm leased 1,100 servers from Carpathia Hosting while Cogent Communications Group also provided servers.