Parliament's Speaker is expected to report back today to an urgent request about MPs emails being monitored, and even blocked, by Parliamentary Service.
Labour's chief whip Chris Hipkins says Parliamentary Service told him it had blocked one of his emails because of a security classification of the attached document, which he says is 'outrageous'.
Mr Hipkins has asked the Speaker of the House to urgently investigate what he says is a clear breach of parliamentary privilege.
He told the House that Parliamentary Service was monitoring, and in some cases blocking, emails to and from MPs based on government security classifications.
When he sought clarification from Parliamentary Service, Mr Hipkins said he was told they had blocked it on the basis the document attached to his email contained "sensitive words" that were in violation of government security classifications.
"And therefore I was not allowed to send the email - that's outrageous, they have no right to be screening the emails being sent by Members of Parliament."
He said the incident had "tipped us [Labour] off" to the fact MPs emails were being monitored.
Mr Hipkins said the document he was sending to a journalist had been released under the Official Information Act.
Speaking to Morning Report today, Mr Hipkins said there was room for abuse in the new system.
He said other MPs and staff have had emails blocked in the last two months, but no-one was informed about a new system.
"They shouldn't be monitoring the emails that I am sending and receiving anyway. I'm not a member of government, I'm an opposition member of the parliament, and from time to time we will be handling information that is embarrassing to the government, that's the nature of what we do."
Mr Hipkins said he expected the Speaker David Carter, to come to the House with a response today, as it was a breach of Parliament's rules, even if software was being used to screen communications.
"And it's something he needs to put an immediate stop to."
The Speaker is responsible for Parliamentary Service, which provides administrative and management services to Parliament.
Mr Hipkins said since he raised it in Parliament, Labour Party staff had been contacting him with other examples of their emails being blocked. Those had all been in the last few weeks so he was not sure how far back this went.
Parliament's Privilege Committee considered how Parliamentary Service handled MPs information, in the wake of the controversy over Peter Dunne and the journalist Andrea Vance.
Mr Hipkins, who was on that committee, said there was discussion among committee members during those hearings about the fact Parliamentary Service should not be monitoring either the metadata or content of MPs communications, and to do so could be matter of privilege.
The National Party's senior whip said it would be concerning if Parliamentary Service has overstepped the mark when dealing with MPs' communications.
Tim Macindoe said he would be interested to hear the Speaker's response this afternoon.
"I think all MPs would be concerned to ensure their legitimate activities are not being interfered with, so I'm hoping that the issue will be resolved quickly."
Parliamentary Service said it had no comment to make, except that it was working with the Speaker on the matter and would know more in the next couple of days.