Update 5.10pm: Sinn Féin leader Gerry Adams has hit out at the deal between the DUP and the Conservatives - saying it’s a "blank cheque for a Tory Brexit".
“The price of today’s DUP-Tory deal is DUP support for continued Tory Austerity and cuts to public services.
“It provides a blank cheque for a Tory Brexit which threatens the Good Friday Agreement.
“The DUP have agreed to support the Tory Government on all motions of confidence; and on the Queen’s speech; the Budget; finance bills; money bills, supply and appropriation legislation and estimates and all legislation pertaining to British national security and Brexit.
“The Tory government has slashed more than £1 billion from the block grant over the last seven years. The allocation of additional funds could help to ease the enormous pressure on our public services. The devil is in the detail.
Arlene Foster has said the deal will help address "the unique cirumstances of Northern Ireand and the affect these have had on the economy and its people".
Earlier: Scottish and Welsh leaders have reacted furiously to a deal struck between the UK Government and the DUP.
Welsh First Minister Carwyn Jones described the agreement - which includes £1bn in new funding for Northern Ireland - as "unacceptable" and a "straight bung" to prop up a "faltering" Conservative minority government while SNP Westminster leader Ian Blackford MP slammed the deal as "grubby".
Downing Street has said that as the allocation is being made as part of the block grant to Northern Ireland, there will be no knock-on funding boost for other parts of the UK through the Barnett formula, the mechanism used to distribute British Treasury funds to the devolved nations.
Mr Jones said: "Today’s deal represents a straight bung to keep a weak British Prime Minister and a faltering Government in office.
"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’.
"This deal flies in the face of that commitment and further weakens the UK, and as currently drafted all but kills the idea of fair funding for the nations and regions.
"It is outrageous that the Prime Minister believes she can secure her own political future by throwing money at Northern Ireland whilst completely ignoring the rest of the UK."
UK Scottish Secretary David Mundell has previously said he "won’t support funding which is deliberately sought to subvert the Barnett rules".
He said: "We have clear rules about funding of different parts of the United Kingdom. If the funding falls within Barnett consequentials, it should come to Scotland."
Mr Blackford said: "After weeks of secret backroom negotiations, the Tories have now signed a grubby deal with the DUP.
"The financial aspects of this deal entirely sum up how little the Tories care about Scotland - while a billion pounds is being handed over to Northern Ireland, Scotland is seemingly to be offered little more than scraps from the table.
"The claim is being made that the funding being made available is a recognition of Northern Ireland’s special circumstances - but if there was any true appreciation of those circumstances, there would be no deal at all with the DUP.
"Only 24 hours ago David Mundell was categorically assuring us that Scotland would be in line for Barnett consequentials as a result of the DUP deal - so he has seemingly either been deliberately misleading people or he is completely out of the loop even in Theresa May’s crumbling government."
He said the deal was "the first big test" for Scottish Conservative leader Ruth Davidson and her new raft of Scottish Tory MPs.
DUP leader Arlene Foster said the deal included financial support of £1bn in the next two years as well as "new flexibilities" on almost £500 million previously committed to Northern Ireland.
She said the money will be used to boost the region’s economy and invest in new infrastructure, health, education and other sectors.
Scotland’s First Minister Nicola Sturgeon tweeted: "Any sense of fairness sacrificed on the altar of grubby DUP deal to let PM cling to power, & Scots Tories influence in No10 shown to be zero".
Any sense of fairness sacrificed on the altar of grubby DUP deal to let PM cling to power, & Scots Tories influence in No10 shown to be zero— Nicola Sturgeon (@NicolaSturgeon) June 26, 2017