The Government has narrowly avoided defeat in the Lords at the hands of peers determined to see the planned high-speed rail network continue to Sheffield and Leeds.

An amendment aimed at committing ministers to legislating for the eastern leg of HS2 from the West Midlands was rejected by 274 votes to 265, Government majority nine.

It followed assurances by transport minister Baroness Vere of Norbiton that the change was unnecessary as plans for the high-speed line to Sheffield and Leeds would be set out in an integrated rail plan.

Former transport secretary Lord Adonis warned it would be a “short-sighted catastrophe” if ministers were to cancel or severely delay this part of the HS2 project.

Lord Adonis said it was “absolutely fundamental” that the new network should not just serve the West Midlands and the North West, but also the East Midlands and Yorkshire.

“If it’s a project just for one half of the country then it will by definition leave the other half behind,” he told the Lords, in report stage debate on the High Speed Rail (West Midlands-Crewe) Bill.

Labour’s Lord Adonis warned a failure to complete the Yorkshire leg of HS2 would be the equivalent of the Victorians building a railway to Manchester but leaving the canals to serve Sheffield and Leeds.

Labour former Cabinet minister Lord Blunkett, backing the move, said: “Unless you get it on paper, unless it’s absolutely unequivocal, it’s not going to happen. And the East Midlands, Yorkshire and the North East will lose out all over again.”

For the Opposition, Lord Rosser said the indications were that the Government was either looking to abandon or scale-back the eastern leg of HS2 to Leeds, or “at best seriously delay its construction and completion”.

But Lady Vere said the amendment calling for the Government to legislate for the eastern leg of HS2 within six months of the Bill becoming law was not needed.

“The Prime Minister has been very clear that the Government’s plans for the HS2 eastern leg will be set out in the integrated rail plan and that this will be laid before Parliament in the same time frame of the amendment,” she said.

Lady Vere said preparations were already under way for phase 2b of the project to Manchester and Leeds in smaller, multiple Bills, which could run concurrently.

“Plans for legislation covering the eastern leg of HS2 phase 2b will be confirmed following the publication of the integrated rail plan.”

Lady Vere said that if Lord Adonis were to withdraw his amendment, she would commit to publish the plan for legislation as part of the integrated rail plan.

But Lord Adonis said her assurances did not go far enough and pressed his amendment unsuccessfully to a vote.