Parliament's website shut down on Friday morning following a threat by a hacker activist group.
The group, which calls itself "Anonymous", threatened on YouTube to block access to the website in protest at recent changes to copyright law aimed at combating internet piracy.
The website was operating again on Friday afternoon, but Parliamentary Services general manager Geoff Thorn will not say whether it was shut down because of the hackers' threat.
The website for the New Zealand Federation Against Copyright Theft was also down on Friday.
The federation's chief executive, Tony Eaton, says he does not know what is to blame.