The ACT Party will support the Government's new legislation on covert surveillance, conditional on an urgent select-committee hearing.
The party's parliamentary leader, John Boscawen, says all five ACT MPs will vote for the bill's first reading and any support after that will be based on the legislation getting select-committee approval.
The Government is putting forward the bill in response to a Supreme Court ruling last week that the use of hidden cameras in the operation that culminated in the 2007 Urewera police raids was illegal.
Police have since suspended covert video surveillance, and the Government says the ruling has thrown evidence in dozens of other operations into doubt.
The new bill allows police to resume using hidden cameras.
National has United Future on board and needs the votes of at least three of ACTs five MPs to pass the legislation before the House rises next month.
Prime Minister John Key says National will continue to negotiate with other parties to secure support and believes ACT understands the need for an urgent law change.
"And they do have a desire, as I understand it, to see the legislation fixed and that to happen before the election.
"But in the end, what terms and conditions is a matter for them and we'll have to continue to work with them, as we'll work with all other political parties to see if we can find a fix to what is I believe a very serious issue for New Zealand."
Case not strong enough, says Labour
The Labour Party says the Government has not yet made a strong enough case to justify rushing through an urgent bill.
The party's justice spokesperson, Charles Chauvel, says the Supreme Court ruling still allows for illegally obtained video evidence to be used in court if a case is serious enough.
He says if the Government wants to bypass the usual parliamentary process, it needs to provide better evidence in justification.
Mr Chauvel says Labour last year offered its support for the Search and Surveillance Bill with four changes aimed at satisfying civil liberties concerns, but it got no response from the Government.