A review of the multibillion-pound plans to repair the Palace of Westminster will not consider whether to move Parliament to York while the work is carried out.

Boris Johnson had asked the body responsible for the project to consider a “possible location outside London” for Parliament to sit while work is carried out to repair the crumbling palace as part of its review of the plans.

But the Restoration and Renewal Sponsor Body and Delivery Authority said it is for MPs and peers to decide where they should sit and it will not form part of the review.

In a letter to the Prime Minister, sponsor body chief Sarah Johnson and delivery authority head David Goldstone said there are “constitutional implications” for moving MPs and peers outside London “which makes this a matter for both Houses to determine rather than for our review”.

“This option will not, therefore, be considered as part of the scope of the strategic review,” they said.

MPs and peers agreed in 2018 to a plan that would see both Houses move to temporary facilities near the existing site – a “full decant” – to allow essential repairs and upgrades to be made to the Victorian palace.

But amid concerns about the cost – estimated at almost £4 billion in 2014 – a review of the plans is being carried out by the sponsor body.

The letter to the Prime Minister noted the “full decant” – rather than a partial move which would see peers and MPs vacate Parliament in turn – had been judged as the “quickest, cheapest and least risky delivery option”.

But the review will consider “whether circumstances have changed so significantly as to warrant reconsidering these options”.

A spokesman for Parliament’s restoration and renewal programme said: “The Houses of Parliament are falling apart faster than they can be fixed.

“As the Prime Minister made clear in his letter, the current situation is unsustainable given the serious risk of a major fire and the need to upgrade services throughout the building.

“The restoration and renewal programme was set up in law, accountable to Parliament, to tackle this urgent work and is currently reviewing how the programme is delivered.

“The option of locating Parliament outside London has constitutional implications, and as the speakers of both Houses have stated, this means it is a matter for both Houses to determine rather than for our review.

“In line with best practice, we remain committed to developing a business case that will set out in detail the options for restoring Parliament, including cost estimates and timescales.”