A "bombshell" combination of UK Government tax breaks and social security cuts will lose Scots around £2 billion by 2021, the shadow Scottish secretary has claimed.

The party commissioned research by the House of Commons Library showing the reduction to the Universal Credit Work Allowance will cut household incomes by £740 million by 2021.

The freeze to working age benefits is expected to reduce household incomes by £760 million by the same time, and the real cost is expected to be higher as the government figures do not account for inflation.

The research shows the expected impact of the two budgets and autumn statements since the last general election, covering 2015/16 to 2020/21.

Shadow Scottish secretary Ian Murray, said: "These figures are shocking and Theresa May and Ruth Davidson should be absolutely ashamed of themselves. Tory cuts on this scale will be a bombshell for Scottish families.

"In the run-up to the Autumn Statement, the Chancellor suggested he would do things differently from his predecessor, but in reality he did nothing of the sort. It's the same old Tory story of tax cuts for the wealthy and just cuts for everyone else.

"Labour called for the cuts to Universal Credit to be scrapped but the Chancellor refused."

He accused the SNP of turning the Scottish Parliament into a "conveyor belt to pass on Tory cuts to the Scottish people", adding: "Rather than reintroduce the 50p rate for the richest few, the SNP has chosen once again to cut the local authority budgets that pay for our schools, care services and hospitals."

The new analysis follows a study last month which found benefit claimants in Scotland are projected to lose out on more than £2 billion a year under UK Government welfare reforms.

Researchers at Sheffield Hallam University put the financial loss to Scottish claimants of cuts announced since the 2015 general election at just over £1 billion a year by 2020-21.

A Scottish Government spokesman said: "The UK Government's welfare cuts and benefits sanctions have pushed more families into crisis. The impact of changes to benefits and tax credits over the last few years is a considerable burden on those least able to afford it and continues to push more and more people into poverty at the very time we want to lift people out of poverty.

"Despite a real terms cut to the day-to-day budget that pays for public services, our 2017-18 Draft Budget delivers increased investment in education, record investment in the NHS, protects low income households from tax hikes and supports more and better jobs.

"We are committed to ensuring Scotland is a country that businesses and people want to locate, live, and work in, both through preserving a competitive, progressive tax environment but also providing good quality public services.

"The local government finance settlement, in addition, taken together with the opportunity to raise additional Council Tax, provides a package of measures that gives additional spending power to support local government services of £241 million."

A UK Government spokesman said: "The best way to support people is to help them into a job, so it is welcome that in Scotland there are a near record 2.6 million people now in work.

"Our welfare reforms are incentivising work, while restoring fairness to the system. And across the UK we continue to spend over £90bn a year on working age benefits to ensure there is a strong safety net.

"We have also repeatedly increased the tax contribution of the wealthy - the share of total income tax paid by the top 1% is 27%; higher than in any year between 1997-2010.

"We are devolving significant new welfare, tax and spending powers to the Scottish Government, and we will continue to work together to ensure that devolution works for the people of Scotland and the UK."