THERESA May has brushed aside a call from MSPs for Scotland to have a bespoke Brexit deal on immigration with the UK Government insisting that, post EU withdrawal, the country "must face the future together as one United Kingdom".

The call from Holyrood’s Culture, Tourism, Europe and External Relations Committee comes as MPs prepare for three days of intense debate on the Prime Minister’s Brexit Bill, which could see almost 30 Conservative MPs defy their leader if she does not guarantee Westminster a so-called “meaningful vote” on the final Brexit deal to enable Parliament to force her back to the negotiating table in the event of a bad outcome.

Labour frontbenchers could also defy their leader on the key Third Reading vote on Wednesday over Jeremy Corbyn’s order that they allow the legislation through. Yet despite the prospect of another rebellion, the Labour leader has hinted those who defy him might escape the sack as he stressed that he was a “very lenient person”.

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As MPs consider more than 100 pages of amendments, including one today on guaranteeing EU citizens’ residency rights, Alex Salmond, the former First Minister, called on MPs to form a cross-party alliance to "call a halt to the Mad Hatter's Westminster Tea Party," stressing how the SNP would fight tooth and nail to "blunt the axe of a hard Brexit".

In its report published today, the Scottish Parliamentary Committee warns that without a bespoke or differentiated option on immigration Scotland could suffer economically and culturally.

Noting how there were 181,000 EU nationals living in Scotland under “imposed uncertainty” about their future status, the MSPs called on the UK Government to provide “clarity” on their residency rights “without further delay”.

They warned: “If these people leave as a result of the prospect or reality of withdrawal from the EU, it has the potential not only to undermine Scotland‘s economic performance but also to reduce the sustainability and cultural diversity of our communities; whether in cities, towns or rural areas.”

It noted how since 2000 half of the increase of those born outside the UK living in Scotland had come from EU nationals compared to just one third in the UK as a whole.

The report noted: “As the majority are of working age, they have increased the size of the working population in Scotland and offset the effects of an ageing population. With higher fertility rates, they have also helped reverse population decline. The Committee, therefore, believes that there are acute risks to Scotland of a loss of the existing EU migrants or a decline in future migration.”

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It added: “EU migrants have enriched our lives and widened our cultural horizons; losing them would leave Scotland a narrower place.”

However, the two Conservative members on the nine-strong cross-party committee made clear the report did not reflect their views on immigration policy in Scotland. Jackson Carlaw and Rachael Hamilton said: "The view of the Scottish Conservative Party is that a sectoral approach to immigration - not a geographic one - is the best way forward to meet skills and demographic needs within the UK."

The Scottish Government welcomed the report, saying it highlighted the importance of EU migration to Scotland and the Scottish economy.

"Any move to strictly limit migration, whether from within or beyond the EU, has the potential to seriously harm our economy," it warned, adding: "There is a growing support for Scotland to be able to determine our own immigration policy and the proposals we published in December would see immigration devolved."

But the UK Government has repeatedly set its face against Scotland having any separate deal or powers over immigration.

Last month, Amber Rudd, the Home Secretary, followed David Mundell, the Scottish Secretary, and Robert Goodwill, the Immigration Minister, in dismissing the idea of a different policy for Scotland.

She said a differentiated option "would complicate the immigration system, harming its integrity" and argued it would cause problems for businesses.

Responding to what he described as the Committee's “call for a bespoke immigration solution in Scotland,” a UK Government spokesman said: “As we leave the EU, we must face the future together as one United Kingdom.”

He added: "We're clear that we want to protect the status of EU nationals already living here and the only circumstances in which that wouldn’t be possible is if UK citizens’ rights in European member states were not protected in return."

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The Joint Ministerial Committee is due to meet once again this week to “intensify” its consideration of the Scottish Government’s call for a differentiated deal, which would include Scotland retaining membership of the single market and having discrete powers over immigration.

On Wednesday, Michael Russell, the Scottish Government Minister for UK Negotiations on Scotland’s Place in Europe, is due to appear before the Commons Brexit Committee.