Green Party MP Keith Locke says there is no reason for submissions on changes to the country's spy laws to be heard behind closed doors.
Parliament's Intelligence and Security Committee will this week consider public submissions on the Security and Intelligence Service Amendment Bill in private.
The bill modernises the law to deal with the monitoring and interception of emails, text messages and other computer data.
Mr Locke says the legislation gives intrusive new powers to the SIS and it is wrong to exclude the public from the hearings.
The Labour Party also wants the hearings to be held in public.
Prime Minister John Key, who chairs the Intelligence and Security Committee, says the Government has nothing to hide, but the default position under the current law is to deal with the matter in private.