The Scottish and Welsh governments have reacted with fury to a deal between the Conservatives and the DUP that will see an extra £1.5 billion of funding go to Northern Ireland but no extra to Scotland and Wales.
The deal, which was announced on Monday morning, does not fall under the Barnett formula, which is used to calculate funding given to devolved governments – meaning the Welsh and Scottish budgets will be unaffected.
The Welsh first minister Carwyn Jones described the deal as a "straight bung to keep a weak prime minister and a faltering government in office", while Scotland's first minister Nicola Sturgeon said it was "the worst kind of pork barrel politics".
"Only last week we were told that the priority was to ‘build a more united country, strengthening the social, economic and cultural bonds between England, Northern Ireland, Scotland and Wales,'" said the Welsh first minister.
"This deal flies in the face of that commitment and weakens the UK, and as currently drafted all but kills the idea of fair funding for the nations and regions. It's outrageous that [May] believes she can secure her own political future by throwing money at Northern Ireland whilst completely ignoring the rest of the UK."
Sturgeon tweeted that the prime minister had agreed the deal to "cling to power" and that it showed the influence of the 13 Scottish Conservative MPs was "zero".
In a later statement, Sturgeon said she and Jones would be seeking "urgent discussions" with the UK government about funding and said the deal "shredded the last vestiges of credibility of this weakened Prime Minister".
“In concluding this grubby, shameless deal the Tories have shown that they will stop at nothing to hold on to power – even sacrificing the very basic principles of devolution," said Scotland's first minister.
“By ignoring the Barnett formula, Scotland will be missing out on an estimated £2.9bn in funding for our public services – that is the price to Scottish taxpayers for the Tories to stay in power.
“This breaks the very principles that underpin devolution and the funding settlement the Tories pledged to protect the Tories’ excuses are simply empty spin, and expose that they once again plan on short-changing Scotland."
“This is not a city deal – it is simply an attempt to pull the wool over people’s eyes. This is the worst kind of pork barrel politics, which has shredded the last vestiges of credibility of this weakened Prime Minister.
“I know that these concerns are shared by the First Minister of Wales, and I will be seeking urgent discussions in the days ahead to stand up for our respective nations for basic fairness.”
SNP MP Tommy Sheppard told BuzzFeed News: "This is a sordid deal that should not stand. If it does then [the government] have abandoned the notion of allocating public funds on the basis of need.
"If they aim to do this by using funding mechanisms for purposes they were not intended for them they must be challenged legally and politically."
He added: "If the Scottish Tories do not oppose this they will be exposed as people determined not to stand up for their constituents for the sake of their party which is clinging onto power by its fingernails."
Fellow SNP MP Pete Wishart told BuzzFeed News: "This isn't a 'coalition of chaos' this is something much, much worse that will leave UK government in thrall to the worst type of social conservatives.
"The sweetener at the heart of the deal also bypasses the normal allocation of funding across the UK through the Barnett Formula. This is the first big test for the self styled 'party within a party' of Scots Tory MPs to stand up for Scotland and secure our nation's equivalent share."
A Scottish Conservative source said the party's MPs would push for more money, saying: "We'll go through the budget process to deliver for Scotland."
The secretary of state for Scotland, David Mundell, previously said he would not support a deal with the DUP if it "sought to subvert the Barnett rules", adding: "We have clear rules about funding of different parts of the UK. If the funding falls within Barnett consequentials, it should come to Scotland."
Mundell has not responded to a request for comment on if he will back the prime minister's deal, but party leader Ruth Davidson said criticism of the UK government from the SNP was "absurd" and Scotland already benefits from spending.
“It’s absurd for the SNP to criticise UK government spending on top of Barnett in Northern Ireland, when the exact same thing happens in Scotland," said the Scottish Conservative leader.
“And it is incredibly hypocritical for the SNP to complain when, under their reckless plans for independence, they would end the UK’s funding deal immediately – leaving Scotland with a £15 billion black hole in our public finances.
“With 13 MPs fighting Scotland's corner from within the party of government, rather than the SNP which will only ever vote against Conservative budgets in the Commons – we can get more done and deliver for Scotland.”