Theresa May’s plan to cut net migration to under 100,000 a year would almost double unemployment in the UK to more than three million, according to a new study.

It claims that British workers would be the main losers from lower economic growth caused by the country having fewer people to drive business expansion and, in turn, consumer demand and spending.

The Migration Matters Trust, a cross-party group of politicians, business leaders and trade unionists which encourages an evidence-based debate on immigration, studied the relationship between the migration, unemployment and employment figures over the past 10 years.

The trust is backing the Drop the Target campaign run by The Independent and the Open Britain group, which urges the Government to abandon its goal of cutting annual net migration to the “tens of thousands”.

It concluded that unemployment would rise from 1.6 million today to 3.1 million if net migration fell below 100,000. It has not stood at that level since the mid-1980s during the Thatcher Government.

According to the study, the employment rate for British citizens – the percentage wanting to work who have jobs – would drop from 75 per cent to 70 per cent, the lowest level for 20 years. The number of jobless people chasing each vacancy would rise from two today to seven.

Barbara Roche, chair of Migration Matters and a former Labour Immigration Minister, said: “It’s not politically correct to say this, but some of the people hit hardest by cutting migration to below 100,000 would be British workers.

"According to the Government’s own figures, in industries like hospitality, which have a higher proportion of migrant workers, seven out of 10 employees are Brits. These are the workers who will suffer if migration is cut.”

She added: “The case for immigration isn’t about abstract altruism but British self-interest. By plugging skills gaps in businesses, immigration safeguards the jobs of British workers in those firms.”

Keith Knowles, chief executive of Beds and Bars, which includes St Christopher’s Inns hostels and Belushi’s bars, said: “Without migrants to help plug skills gaps, my business would really struggle.

UK General Election 2017 Show all 47 1 /47 UK General Election 2017 UK General Election 2017 12 June 2017 British Prime Minister Theresa May leaves 10 Downing Street for the 1922 committee on June 12, 2017 in London, England. British Prime Minister Theresa May held her first cabinet meeting with her re-shuffled team today Getty Images UK General Election 2017 12 June 2017 DUP leader Arlene Foster stands alongside deputy leader Nigel Dodds as they hold a press conference at Stormont Castle as the Stormont assembly power sharing negotiations reconvene following the general election on June 12, 2017 in Belfast, Northern Ireland. Discussions between the DUP and the Conservative party are also continuing in the wake of the UK general election as Prime Minister Theresa May looks to form a government with the help of the Democratic Unionist parties ten Westminster seats. Stormont and the political situation in Northern Ireland has been in limbo following the collapse of the power sharing executive due to the Renewable Heat Incentive scheme scandal which implicated the DUP Getty Images UK General Election 2017 12 June 2017 Priti Patel, International Development Secretary leaves 10 Downing Street Getty Images UK General Election 2017 12 June 2017 Larry the Downing Street cat runs ahead of Michael Fallon Britain's Secretary of State for Defence as he arrives for a cabinet meeting at Downing Street in London, Britain, June 12, 2017. REUTERS/Stefan Wermuth REUTERS UK General Election 2017 12 June 2017 Michael Gove, Environment Secretary leaves 10 Downing Street on June 12, 2017 in London, England. British Prime Minister Theresa May held her first cabinet meeting with her re-shuffled team today Getty Images UK General Election 2017 12 June 2017 Scottish National Party Leader Nicola Sturgeon (C) leaves after speaking to the media in Parliament Square. Getty Images UK General Election 2017 12 June 2017 British Prime Minister Theresa May (C, L) holds the first Cabinet meeting of her new team. Getty UK General Election 2017 11 June 2017 British Prime Minister Theresa May attends church in her constituency with her husband Philip May, a few days after disappointing results in a general election. Rex Features UK General Election 2017 9 June 2017 Leader of the Labour Party Jeremy Corbyn leaves Labour Party HQ this morning, following a general election yesterday. Parliament is hung, with no individual party gaining an overall majority. Post general election reaction. Rex UK General Election 2017 9 June 2017 BELFAST, NORTHERN IRELAND - JUNE 09: DUP leader and Northern Ireland former First Minister Arlene Foster (C) holds a brief press conference with the DUP's newly elected Westminster candidates who stood in the general election Getty Images UK General Election 2017 9 June 2017 A " Get May Out" demo took place opposite the gates of Downing Street, calling for May to resign, after the shock election results and Mays coalition with the DUP. Rex Features UK General Election 2017 9 June 2017 A demonstrator wears a mask depicting Britain's Prime Minister and leader of the Conservative Party Theresa May, poses with a mock gravestone bearing the words "Hard Brexit, RIP", during a protest photocall near the entrance 10 Downing Street in central London AFP/Getty Images UK General Election 2017 9 June 2017 Britain's Prime Minister Theresa May arrives at the Conservative Party's headquarters in London Reuters UK General Election 2017 9 June 2017 Britain's Prime Minister and leader of the Conservative Party Theresa May flanked by her husband Philip delivers a statement outside 10 Downing Street in central Londo Getty UK General Election 2017 9 June 2017 Britain's Prime Minister and leader of the Conservative Party Theresa May leaves Buckingham Palace in London the day after a general election in which the Conservatives lost their majority Getty Images UK General Election 2017 9 June 2017 A TV cameraman watches the door of 10 Downing Street in London Getty Images UK General Election 2017 9 June 2017 Labour leader Jeremy Corbyn is greeted by his Office Director Karie Murphy as he arrives at Labour Party HQ in Westminster, London, after he called on the Prime Minister to resign, saying she should 'go and make way for a government that is truly representative of this country' Dominic Lipinski/PA Wire UK General Election 2017 9 June 2017 Britain's Prime Minister Theresa May arrives at the Conservative Party's headquarters with her husband Philip in London REUTERS/Peter Nicholls UK General Election 2017 9 June 2017 Ukip leader Paul Nuttall speaks during a press conference at Boston West Golf Club where he announced that he is standing down as party leader Joe Giddens/PA UK General Election 2017 9 June 2017 Ruth Davidson, leader of the Scottish Conservatives, leaves the counting centre for Britain's general election with her partner Jen Wilson in Edinburgh, Scotland REUTERS/Russell Cheyne UK General Election 2017 9 June 2017 Scottish Labour leader Kezia Dugdale celebrates with candidate for Edinburgh South Ian Murray as he retains his seat at the Meadowbank Sports Centre counting centre in Edinburgh, Scotland Getty Images UK General Election 2017 9 June 2017 First Minister Nicola Sturgeon speaks to the media at the Emirates Arena in Glasgow, as counting is under way for the General Election Andrew Milligan/PA Wire UK General Election 2017 9 June 2017 Scottish Conservative leader Ruth Davidson at Meadowbank Sports Centre in Edinburgh, as counting is under way for the General Election PA UK General Election 2017 9 June 2017 Scottish National Party (SNP) leader Nicola Sturgeon reacts at the Emirates Arena in Glasgow, Scotland EPA UK General Election 2017 9 June 2017 Jeremy Corbyn, leader of Britain's opposition Labour Party, arrives at the Labour Party's Headquarters in London REUTERS/Marko Djurica UK General Election 2017 9 June 2017 UKIP Leader Paul Nuttall leaves in a car following the vote count for the constituency of Boston and Skegness in Boston, England Anthony Devlin/Getty Images UK General Election 2017 9 June 2017 British Prime Minister and Conservative Party leader Theresa May speaks at the declaration at the election count at the Magnet Leisure Centre in Maidenhead, England. Getty Images UK General Election 2017 8 June 2017 A policer officer enters a polling station in London AP UK General Election 2017 8 June 2017 A woman leaves after casting her vote at the Hove Museum and Art Gallery near Brighton, in southern England Getty UK General Election 2017 8 June 2017 A polling station sign is seen on a telephone box outside the polling station at Rotherwick Hall, west of London Getty UK General Election 2017 7 June 2017 A woman walks past a general election display in the window of a betting shop in Camden on June 7, 2017 in London, United Kingdom. Britain goes to the polls tomorrow, Getty Images UK General Election 2017 7 June 2017 Britain's Prime Minister Theresa May visits Atherley Bowling Club during an election campaign visit on June 7, 2017 in Southampton, England. Britain goes to the polls tomorrow June 8 to vote in a general election. Getty Images UK General Election 2017 6 June 2017 A supporter wears a pair of Jeremy Corbyn decorated tights at a general election campaign event in Birmingham, central England, on June 6, 2017. Britain goes to the polls on June 8 to vote in a general election only days after another deadly terror attack in the nation's captial. AFP/Getty Images UK General Election 2017 6 June 2017 A picture taken in London, shows election leaflets from various parties displayed ahead of the United Kingdom's general elections. Britain goes to the polls on June 8 to vote in a general election only days after another terrorist attack on the nation's capital AFP/Getty Images UK General Election 2017 6 June 2017 Election workers, George Gaunt and Luca Tragid deliver the first ballot boxes, on the Royal Mile in Edinburgh AFP UK General Election 2017 6 June 2017 British Prime Minister Theresa May meets with Conservative party supporters during an election campaign visit to a bakery during an election campaign visit on June 6, 2017 in Fleetwood, north-west England. Britain goes to the polls on June 8 to vote in a general election only days after another terrorist attack on the nation's capital Getty Images UK General Election 2017 5 June 2017 British Prime Minister Theresa May speaks during a general election campaign visit to a removals depot in Edinburgh AFP/Getty Images UK General Election 2017 3 June 2017 Pro-Independence supporters hold a march through Glasgow AFP/Getty Images UK General Election 2017 3 June 2017 Opposition Labour Party leader Jeremy Corbyn campaigns for the upcoming general election in Beeston, Nottinghamshire AFP/Getty Images UK General Election 2017 3 June 2017 Labour leader Jeremy Corbyn reacts to supporters after a rally at Beeston Youth and Community Centre as he visits the East Midlands during the final weekend of the General Election campaign on June 3, 2017 in Nottingham, England. If elected in next week's general election Mr Corbyn is pledging to create a million new jobs and to scrap zero-hours contracts Getty Images UK General Election 2017 1 June 2017 Scottish Conservative and Unionist Party leader Ruth Davidson joins a selection of Scottish Conservative election candidates and activists during campaigning on May 1, 2017 in South Queensferry, Scotland. With only seven days to go until the general election on June 8th, polls are showing the SNP out in front and the Conservatives set to close in on Labour. Getty Images UK General Election 2017 29 May 2017 Prime Minister Theresa May canvasses in Richmond with Conservative candidate Zac Goldsmith on May 29, 2017 in London, United Kingdom. After suffering defeat in the London Mayoral election Zac Goldsmith resigned over the Government's position on Heathrow expansion. He stood as an Independent but lost in a by-election to the Liberal Democrats. Britain goes to the polls on June 8 to elect a new parliament in a general election Getty Images UK General Election 2017 22 May 2017 Liberal Democrat leader Tim Farron poses for a selfie taken by carer April Preston during a General Election campaign visit to the Barlow Medical Centre, in Didsbury, Manchester Yui Mok/PA UK General Election 2017 22 May 2017 Britain's Prime Minister Theresa May speaks at an election campaign event in Wrexham, Wales Reuters UK General Election 2017 22 May 2017 Britain's main opposition Labour Party leader Jeremy Corbyn, and Labour's former deputy Prime Minister, John Prescott, exit the party's general election campaign 'battle' bus as they arrive at an event in Kingston upon Hull, northern England Getty Images UK General Election 2017 22 May 2017 Britain's main opposition Labour Party leader Jeremy Corbyn walks with supporters between venues, before speaking again at another general election campaign event in Kingston upon Hull, northern England Getty Images UK General Election 2017 22 May 2017 An anti-fox hunting protester is taken away and arrested by police outside the venue where Britain's Prime Minister Theresa May was due to launch the Welsh Conservative general election manifesto at Gresford Memorial Hall in the village of Gresford, near Wrexham, North Wales, on May 22, 2017. Britain goes to the polls on June 8 to elect a new parliament in a general election AFP/Getty Images

“Migrant workers in my trade are often mislabelled as doing low skill jobs. This is not the case.

“They have a passion for hospitality, something that we really struggle to find here in the UK. For me, migrants are incredibly valuable. Their skills and capabilities keep the business running.

“The UK becomes increasingly unattractive to invest in if we're unable to obtain the skills we need. For us to be able to grow our economy, we need to be able to access the full labour market.”

Chuka Umunna, Labour’s former shadow Business Secretary and a leading supporter of Open Britain, said: “This report sets out the real dangers the Government’s misguided, illogical immigration target poses to our economy.

“People who come to our country from abroad work hard, contribute, found businesses that employ British workers, and pay their taxes.

Michael Fallon says Tories have not costed immigration proposals

“An artificial cap on numbers will make British people worse off. As well as keeping Britain in the single market and customs union after Brexit, the Government needs to ensure that Britain remains open to talented people from Europe and around the world.”

Net migration fell to 248,000 in 2016, down 84,000 on the previous year, according to official figures published on Thursday, due to more people leaving, especially EU citizens, and fewer arrivals.

The controversial target was reaffirmed in the Conservatives’ election manifesto, after Ms May rejected pleas from several ministers to drop it on the grounds that it was unlikely to be hit.

Ministers have refused to put a timescale on when it will be met, and argue that this makes it impossible to calculate the target's economic impact. They have promised a flexible approach to EU migration after Brexit to help business adjust.

Ms May has denied that senior Cabinet ministers opposed her goal. In a BBC interview, she said: “People do support the immigration target and what they’re supporting is the view of the British people. That’s what we’re supporting. Because the British people want to see us controlling migration.”

Experts are divided over the economic impact of lower migration. The Office for Budget Responsibility, the independent fiscal watchdog, estimated last November that a 80,000 drop in net migration would create a £6bn-a-year hole in the public finances by 2020-21.

The Centre for Economic and Business Research found that cutting migration to below 100,000 would reduce the size of the British economy by between 1.5 per cent and 3 per cent by 2025. It highlighted the need to plug skills gaps to ease bottlenecks as a key driver of whether the economy grows or stagnates.

Jonathan Portes, Professor of Economics and Public Policy at King’s College, London, has said there is strong evidence that arbitrary cuts in migration would make the UK less prosperous, and could reduce GDP per head by several percentage points by 2030.

But David Goodhart, Head of Demography, Immigration and Integration at the Policy Exchange think tank, has questioned the OBR’s assumptions.

He said: “If the Government continues with its current policy of encouraging higher skilled immigrants and discouraging lower skilled immigrants, especially from the EU after the end of free movement, then it should be possible to reduce numbers without reducing the high fiscal contribution from French and German bankers.

“And the OBR seems to take no account of the possibility that lower immigration might mean higher wages and more automation increasing productivity, incomes and thus the fiscal contribution of the average worker.”

If you agree, please sign our petition to call on the Government to Drop The Target: