MPs on all sides are joining forces to defend the right to set their own unlimited travel perks - despite a Government promise to transfer them to an independent body.

Prime Minister John Key pledged three years ago that the Government would strip MPs of the power to set their own perks. It introduced a bill last year to change the system, under which Parliament's Speaker determines the widely criticised allowances that give MPs unlimited free travel within New Zealand.

However, MPs on the government administration select committee have gutted the Members of Parliament (Remuneration and Services) Bill - and returned control of travel and accommodation perks to the Speaker. The U-turn has received cross-party support.

Mr Key has accepted the changes and says National MPs will vote for the amended bill when it came before Parliament again.

Labour leader David Shearer's office said his MPs would not oppose the changes, and Greens co-leader Metiria Turei said her party had agreed to them.

The Speaker's power to set the allowances has long been criticised as a case of MPs determining their own perks. A Law Commission report recommending switching control of the perks to the Remuneration Authority was accepted by Mr Key in 2010.

Former Law Commission head Sir Geoffrey Palmer said he was "sad" the recommendations had been overturned.

Political scientist Bryce Edwards said he was surprised by the U-turn, because MPs had made such a "big deal" of the proposed switch to an independent body.

"It's a bad look for it to be coming back to the MPs," he said.

When Mr Key accepted the commission's reforms, he hailed them as necessary and important - a new direction that increased transparency, accountability and independence.

A spokeswoman for Mr Key said this week: "The prime minister has consistently been an advocate for the principle that an independent body should set these entitlements.

"This bill makes further steps in that direction and the prime minister is confident it will be seen as a positive development," she said.

"Given the nature of the legislation, achieving cross-party support was important - and that has been achieved."

One part of the original bill's reforms remains. The amended version still gives the authority the power to set travel perks for MPs' family members.

Labour MP Ruth Dyson, chairwoman of the select committee that gutted the bill, said it had decided the Speaker was the appropriate body to set the allowances.

Travel to and from Parliament was part of an MP's job, she said. She hoped the public would understand that "we travel to Wellington because we're elected to Parliament, not because being in Wellington three days a week is where we would like to be".

Mr Shearer did not respond to calls yesterday, and a Labour spokeswoman said he would not be commenting on the matter. However, she said Labour would not be opposing the Speaker retaining control over travel perks.

Other aspects of the bill might or might not be supported by Labour, she said.

Ms Turei said the Greens had agreed to the changes because the amended bill still represented progress.

However, the party still believed travel allowances should be set by the Remuneration Authority rather than the Speaker, and might propose amendments when the bill was debated again in Parliament.

HOW THE REFORMS WERE NEUTERED

The original Members of Parliament (Remuneration and Services) Bill transferred the power to set MPs' travel and accommodation perks from the Speaker to an expanded Remuneration Authority.

It also transferred control of ministers' travel and accommodation perks from the minister responsible for Ministerial Services (John Key) to the authority. But the government administration select committee reversed both these changes, returning control of the perks to the Speaker and the minister.

One bit of the original bill's reforms remains. The authority still has the power to set travel perks for MPs' family members.