The HS2 high-speed rail link must not terminate in west London, the Mayor has said.

Sadiq Khan said ending HS2 outside the centre would put huge pressure on the new Elizabeth line and “fundamentally undermine” it.

Under current plans, HS2 will run underground from Euston to a new station at Old Oak Common, near Willesden Junction.

It will provide a high-speed link to Birmingham, and eventually the north of England and Scotland.

Trains will run at up to 250mph, cutting journey times to the West Midlands by half an hour.

But costs have ballooned from £62 billion to £80 billion, and the Government is now reviewing the viability of the entire project.

One proposal is to scrap the Euston to Old Oak Common section of the line, so passengers would change to the Crossrail in west London.

But Mr Khan said yesterday (Thursday) that this would have drastic consequences for transport in the capital.

Speaking at Mayor’s Question Time, he said: “Terminating the HS2 service at Old Oak would mean the Elizabeth line would be full by the time it reaches central London, fundamentally undermining its benefits.

“But even Euston’s current Tube connections won’t be able to cope with a fully built HS2 which is why we need Crossrail Two.”

“Similarly if there is no Old Oak station then the Victoria and Northern lines won’t be able to cope with the capacity and demand at Euston.“Having the stations at Old Oak and Euston will ensure HS2 brings much needed relief to many commuter lines into London.”

The Mayor reiterated his support for the high-speed rail project, emphasising the potential for new jobs, growth and regeneration in the capital.

He added: “Rather than speed the focus should instead be on creating new capacity.”

A spokesperson for the Department of Transport said: “The new Secretary of State has established an independent review into HS2 which will provide the department with clear advice on how and whether the project should proceed.

“We are not going to pre-empt or prejudice this work with a running commentary on the review’s progress.”