Council of Trade Unions secretary Peter Conway said asking for access to private pages on Facebook would be "a gross invasion of privacy" similar to demanding to see personal letters.
However, looking at information people chose to allow into the public domain was legitimate. He said job hunters confronted with requests for access to private pages should talk to a workers' advocate group, the Human Rights Commission or the Privacy Commissioner.
Business NZ chief executive Phil O'Reilly also said he would not support such a practice in principle. He said it was possible an employer might be able to argue that they required access to that information in some circumstances. However as a general rule he did not think it was reasonable.
Ms Shroff said people should be careful about what they put on their Facebook sites - a Privacy Commission UMR survey had shown 11 per cent of people regretted putting information on Facebook.
The number who changed their privacy settings on Facebook had increased by 14 per cent in the last two years, "which is quite significant."
Her office had joined NetSafe in trying to ensure schoolchildren knew about the dangers of putting information on sites such as Facebook.