Immigrants arrived in Britain at the rate of almost one every minute during the ‘open door’ years under New Labour, a devastating audit reveals.

The influx caused the foreign population to swell by 3.6million between 1997 and 2010.

The figure was four times higher than the previous 13 years and equivalent to the population of Britain’s five largest cities outside London – Birmingham, Leeds, Glasgow, Sheffield and Bradford.

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One-way ticket: Polish migrants from Zychlin board a coach in Warsaw to start a new life working in Britain

The report was released as immigration – ranked the second most important issue by voters – finally came to prominence in the general election campaign.

Ukip leader Nigel Farage came under attack from both the Tories and Labour after ditching his party’s commitment to cap net immigration at 50,000.

And Ed Miliband attempted to seize the initiative on the issue, ridiculing David Cameron at Prime Minister’s Questions over the Tories’ failure to reduce net migration to the ‘tens of thousands’.

Today the spotlight switches back to Labour’s own record, following the publication of a comprehensive study by the think-tank MigrationWatch.

It found that, through a combination of deliberate policies and ‘cock-up’, 7.23million immigrants were allowed to arrive in the UK – almost one every minute.

The figure includes relatives and children who accompanied their parents – but not offspring born to parents since arrival in the UK.

Ed Miliband attempted to seize the initiative on the immigration issue at Prime Minister’s Questions yesterday over the Tories’ failure to reduce net migration to the ‘tens of thousands’

Discounting the number who left over the same 13-year period, net foreign immigration was 3.6million. However, the figure also excludes the huge numbers who are suspected of sneaking into the country illegally.

Factors behind the surge in arrivals included the relaxation of visa rules for non-EU workers, a five-fold rise in foreign students as bogus colleges flourished and an ‘amnesty’ for more than 200,000 asylum seekers and illegal immigrants.

Labour also made it harder for border guards to stop suspected sham marriages. But the most decisive factor was the party’s decision not to impose controls in 2004 when Poland and seven other former Eastern Bloc countries joined the EU. Ministers predicted only 13,000 would arrive each year – yet more than one million came.

The MigrationWatch study argues that the mass immigration policy had such huge implications it should have been outlined in Labour’s election manifestos.

But in 1997 the only reference was that ‘every country must have firm control over immigration and Britain is no exception’.

The think-tank’s report says: ‘The New Labour years were characterised by a change in culture that was not shared by the wider public.

‘The mood at the top of government circles... was distinctly internationalist in its outlook and viewed national borders as an increasingly archaic feature in this new globalised world.’

The BBC is blamed for stifling debate on the subject, while anyone who dared to voice their concerns risked being ‘thought to be racist’.

Damagingly for Mr Miliband, the analysis concludes that Labour may pursue similar policies if it returns to power – pointing out that the party leader forgot to mention immigration in his conference speech last year. Labour refuses to impose a target for net migration and has said it would remove foreign students from figures.

MigrationWatch also points out the failure of Mr Cameron to meet his ‘tens of thousands pledge’ – with official figures last week showing net migration was almost 300,000 in the year to September 2014.

Ukip leader Nigel Farage came under attack from both the Tories and Labour after ditching his party’s commitment to cap net immigration at 50,000

But it warns Labour is ‘unable to capitalise on the Conservative failure as their legacy on the issue is as close to toxic as is possible’.

MigrationWatch chairman Lord Green of Deddington said: ‘This is a fascinating but very sad story of how a small but determined group appear to have manipulated immigration policy while deterring any opponents with false allegations of racism.’

It doubted Labour would reduce the scale of immigration to a ‘sensible level’ and said pressure from pro-immigration groups would ‘very likely lead to the gates being thrown open once more’.

The report by the independent think-tank says one possible explanation for Labour’s policy was a desire to win future elections.

Once settled in the UK, migrants were entitled to apply for citizenship and vote in general elections.

Labour also decided not to strip voting rights from one million people from the Commonwealth living in Britain who do not have citizenship.

Under arcane rules, they can register on the electoral roll as long as they have an address in Britain.

Open borders dogma that led to anarchy

Through deliberate policy changes and rank incompetence, Labour presided over the largest wave of immigration in modern history. Here, JAMES SLACK examines the key decisions which brought 3.6million foreign nationals to Britain...

EASTERN EUROPE

Labour, unlike in almost every other major European economy, opted not to impose transitional controls when eight former Eastern Bloc countries joined the EU in 2004. Officials predicted only 13,000 would arrive. What followed was one of the largest peacetime movements of people in European history. At the end of 2004, there were 167,000 Eastern Europeans in the UK. Within two years the number had increased by 250,000. The total now stands at 1.077 million.

Under Labour, Britain developed a reputation as a soft touch for asylum seekers – with gangs massing at Calais to try to leap aboard lorries or Eurostar trains. Pictured, illegal immigrants attempt to board a lorry

ILLEGAL IMMIGRANT AMNESTY

More than 220,000 failed and delayed asylum-seekers and migrants were granted permission to stay permanently from 2006 onwards in what was dubbed an effective amnesty. In many cases, the applicants had been stuck in the system for so long that it would have been a breach of their human right to a family life to kick them out. The Tories inherited a backlog of a further 368,100 cases from Labour in 2010.

WORK VISAS

The rules for letting non-EU workers into the UK were relaxed, allowing skilled migrants to come in without first having a job offer. This was a deliberate strategy designed to produce economic growth. In 1997, 62,975 visas were granted to non-EU migrants for work, plus their dependants. By 2005 that figure had more than doubled to at least 137,035 a year.

Tony Blair launched his Prime Minister’s Initiative to in 2009 to increase dramatically the number of non-EU students - but 50,000 students were bogus

BOGUS STUDENTS

In 1999 Tony Blair launched his Prime Minister’s Initiative to increase dramatically the number of non-EU students. Numbers duly rocketed from 39,000 in 1997 to 180,000 a year by the time Labour lost power in 2010 – but little care was taken over who was coming in. The National Audit Office found that in 2009 as many as 50,000 bogus students may have entered the UK to work rather than study.

PRIMARY PURPOSE RULE

One of the new Government’s first acts in 1997 was to abolish a rule that placed the burden on foreign spouses to prove that it was not the primary purpose of their marriage to a British citizen or settled person to obtain residency in the UK. Immediately, it led to a sharp jump in the number of marriage visas – 32,200 were given out in 1998 compared to 21,000 in 1996.

ABOLITION OF EXIT CHECKS

In 1998 Labour abandoned the system of logging people out of the country. The report claims this is likely to have led to more people overstaying their visas and becoming illegal immigrants. In 1997 17,000 citizens of the New Commonwealth departed – this number fell to 10,000 in 1998 when the checks were scrapped.

ASYLUM CHAOS