Dunedin's Labour MPs were not allowed to speak on the matter and leader Andrew Little had not commented by last night.
Public sector representatives, meanwhile, say the move does not give moral authority to the Government in upcoming pay negotiations.
Mr Key will use urgent legislation to overhaul the Remuneration Authority Act, following anger at the size of MPs' pay increases.
MPs' pay will now be pegged to the average public sector pay increase for the previous year.
That means the latest pay rise will now be between 1% and 2% - with the Government taking more advice before revealing the exact amount.
Dunedin-based Green Party co-leader Metiria Turei said in a press release the Greens had pushed for a fairer system for MP pay for a long time, and were glad the Government had listened.
Dunedin South MP Clare Curran and Dunedin North MP David Clark both declined to discuss it when contacted yesterday.
Mr Little was the only person in the party authorised to comment on the move.
Dunedin-based list MP Michael Wood- house said the Prime Minister's response was a very sensible one.
''I hope it is supported by all parties.''
Public Service Association national secretary Richard Wagstaff said the move was a political distraction.
''Now they think they have the moral authority to tell everyone else, no matter how badly paid, they don't deserve a pay rise.''
''[MPs] have basically kept up with inflation, and what they're saying is they'd like to keep up.
''We have a hefty catch-up before we can go into the future with a keep-up [pay rise].''
Last Thursday, the Remuneration Authority announced MPs' pay would increase by 5.5% - which translated to a $8200 rise for backbenchers.
The authority said that once a reduction in the travel entitlement was taken into account, pay packages would increase by 3.5%.
Mr Key said legislation would be passed in urgency so that pay increase could be brought down.
There was a chance back pay might be paid next week, in which case politicians would have to pay the money back or have future wages deducted, Mr Key said.
Asked about forthcoming public sector pay negotiations, Mr Key said the Government had previously asked people to ''show restraint''.
''And, fundamentally, we are asking them to show restraint in the future.''
Clutha-Southland MP Todd Barclay and Waitaki MP Jacqui Dean could not be reached for comment last night.
- Staff reporter & Nicholas Jones of The New Zealand Herald