Gordon Brown saw off a backbench revolt on planning last night but is facing one on road tax next week.

In a speech today the Prime Minister will hail the move to give a new infrastructure planning commission (IPC) key powers on projects such as nuclear plants and airport extensions as a sign of government leadership on cutting carbon emissions. His Commons majority of 65 was cut to 43 when MPs voted on his proposals to speed up decision-making on big infrastructure projects. The Labour rebellion would have been far larger but for last-minute concessions that Mr Brown approved.

His relief may be shortlived, however. Last night Labour MPs gave notice that they would seek to amend Alistair Darling's Budget proposals on vehicle excise duty to stop higher charges applying retrospectively to high-emission vehicles bought after 2002. MPs believe the plans to be deeply unfair on drivers who bought the cars with no warning that they would one day be taxed more highly than others. They want a firm pledge from the Chancellor that the issue will be tackled in the Pre-Budget Report.

The planning victory came as Labour whips picked off the rebels with a series of amendments. Geoff Hoon, the Chief Whip, delayed proceedings to allow more talks with ministers.

Ministers offered to review the new commission after two years and to retain a role for ministers in plans involving issues of national security.

Hazel Blears, the Communities and Local Government Secretary, said that the new system would avoid a repeat of the protracted seven-year planning process over Heathrow Terminal 5.

National policy statements would set out the country's requirements for key infrastructure projects, she said, and would be the subject of a “national debate”, with public and parliamentary involvement, which would then provide a framework for the commission to make decisions about individual projects. This was “a far more transparent degree of accountability than leaving ministers to wait right until the end of the process and then seeking to intervene”, Ms Blears said.

She said that ministers had also agreed to amend the Bill in the Lords to ensure that if the review “revealed problems, it can in future extend the grounds so that ministers can intervene to remove decisions from the IPC and take decisions themselves”.

John Grogan, MP for Selby, who led the Labour rebels, said that the Government's amendments would cause massive confusion and uncertainty for business.

Infrastructure planning involved “tough and very controversial decisions — all the more important that they have democratic legitimacy”, he said. “Otherwise we are going to have a whole load of protests slowing-up these national infrastructure projects.”

Urging peers to take up the issue, Mr Grogan said: “We need to make a clear statement that we aren't happy on grounds of certainty for business and on grounds of democracy.”

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