A recommendation that HS2 should continue to be built in full despite soaring costs has been welcomed by political leaders in the North.

The leaked early draft of a report seen by The Times stated that the high-speed railway should go ahead as “large ticket price rises” will be needed to discourage peak-time travel unless it is built.

The review, led by former HS2 Ltd chairman Douglas Oakervee, found that HS2 could boost cities in the North and Midlands more than London due to better connections on intercity routes.

It also claimed there are no “shovel-ready” alternative schemes to raise capacity on the existing railway.

Connecting Britain, a coalition of business and cross-party political leaders, welcomed the findings while insisting that Northern Powerhouse Rail (NPR) – a plan to transform train services across the region – must be delivered at the same time as HS2.

Manchester City Council leader Sir Richard Leese said: “We welcome this apparent acknowledgement that HS2 will boost the North and begin to level up decades of under-investment in our regions.

“But we still don’t expect the Oakervee review’s final report until later this autumn and so in the meantime we will continue to present the case that HS2 and NPR need to be delivered together, in full.”

Leeds City Council leader Judith Blake added that giving the go-ahead to HS2 and NPR “would be a clear signal from any future government that it recognises the historic under-investment in transport infrastructure outside London”.

Mr Oakervee raised a series of concerns in relation to HS2, notably that its latest cost estimate of £88 billion is expected to increase further.

HS2 was allocated £56 billion in 2015.

The review calculated that rising costs have slashed the estimated benefit to taxpayers for every £1 spent from £2.30 in 2017 to as little as £1.30 this year, The Times reported.

Mr Oakervee also found that the procurement strategy for Phase 1 has been a failure due to inflated prices.

The review was launched by Prime Minister Boris Johnson in August.

It was due to be completed this autumn, but had not been finalised before the General Election was called.

Its findings will be delivered to the new government.

Phase 1 of HS2 is planned to run between London and Birmingham.

It was initially planned to launch in 2026, but a recent report by HS2 Ltd stated that this could be pushed back until 2031.

Current designs involve a second Y-shaped phase launching in two stages: Phase 2a from the West Midlands to Crewe followed by phase 2b from Crewe to Manchester, and Birmingham to Leeds.