Theresa May has been accused of jeopardising peace in Northern Ireland, after reaching a £1 billion deal with the Democratic Unionist Party to prop up her minority Government.

The deal struck in 10 Downing Street after negotiations stretching 18 days since the June 8 General Election also saw the Conservatives formally ditch plans to abolish the triple-lock protection for state pensions and means-test the winter fuel payment during this Parliament.

Under a “confidence and supply” arrangement intended to last until 2022, the DUP guaranteed that its 10 MPs will vote with the Government on the Queen’s Speech, the Budget, and legislation relating to Brexit and national security.

Together with the 317 Tory MPs remaining after Mrs May’s disastrous decision to call a snap election, this will allow the Prime Minister to pass the 326 figure required for an absolute majority in the House of Commons, ensuring her victory in key divisions and protecting her Government from collapse.

Speaking after talks in Number 10 with DUP leader Arlene Foster, Mrs May said the two parties “share many values” and the agreement was “a very good one”.

The agreement would “enable us to work together in the interests of the whole United Kingdom, give us the certainty we require as we embark on our departure from the European Union, and help us build a stronger and fairer society at home”, said the Prime Minister.

Mrs Foster said she was “delighted” with a package which includes £1 billion of new funding for infrastructure and health, along with enhanced flexibility on almost £500 million of previously allocated cash.

The cash will go to the Northern Ireland executive if the devolved institutions are restored by the deadline of June 29. If direct rule is reimposed, the money would remain available, but would be controlled from London.

There were immediate demands for similar largesse for other parts of the UK, with the Welsh executive saying the principality was due almost £1.7 billion under the so-called “Barnett formula” which governs how money is distributed between the four nations.

Welsh First Minister Carwyn Jones described the payment as a “straight bung to keep a weak Prime Minister and a faltering Government in office”.

And the Scottish National Party’s Westminster leader Ian Blackford insisted Scotland should get “its fair share”.

Denouncing the “grubby” deal with the DUP, Mr Blackford said: “For years the Tories have been cutting budgets and services, but suddenly they have found a magic money tree to help them stay in power.”

Downing Street said the Barnett formula does not apply to the new money as it is being provided as an addition to the Northern Ireland Executive’s block grant.

Labour branded the deal “shabby and reckless”, and warned it would undermine the trust in the impartiality of the British Government which was vital to the implementation of the Good Friday Agreement.

“For the Government to be putting such an agreement in jeopardy just to prop up this dismal Prime Minister is nothing short of a disgrace,” shadow foreign secretary Emily Thornberry told the House of Commons.