The illegal surveillance issue adds to a list of missteps in the Megaupload case, including the use of to search Dotcom's house and the to the U.S.

Dotcom and his colleagues are sought by the U.S. on charges of criminal copyright violations and fraud for running Megaupload, a file-sharing site that U.S. prosecutors say rewarded users for trading files without permission of copyright holders. The U.S. Department of Justice alleges Megaupload collected US$175 million in criminal proceeds.

Extradition hearings are expected to begin in March.