Britain’s population could hit 80 million if the country votes to remain in the European Union (EU), Brexit campaigners have warned.

Speaking on the BBC’s Andrew Marr Show, former Mayor of London Boris Johnson said uncontrolled mass immigration caused by the EU’s free movement policies means that Britain could “grow the size of a city like Newcastle every year” to “70 or perhaps 80 million”.

The former London Mayor said he wanted to cut net migration, adding that the only way to achieve that was to leave the European Union. He also challenged the Remain campaign to set out how it would control immigration while maintaining the EU’s rules.

“What the Remain campaign have to say is what is their vision for this? Where are they going to build the homes? What is going to happen to the green belt? How will it work for schools and hospitals and all the public services that will be affected?” he asked, adding: “We’re not hearing anything.”

Meanwhile, Justice Secretary Michael Gove also committed to lowering net migration to the “tens of thousands” after Brexit, something Prime Minister David Cameron promised to implement six years ago but has so far failed to achieve.

In April, a leaked government report said that mass immigration from the European Union was having a “disproportionate” impact on Britain and damaging social cohesion.

The document stated that citizens of other EU states account for 75 per cent of the growth in the UK’s employment figures, with Eastern Europeans especially taking low-skilled jobs and then having their income topped up by “generous in-work benefits, without having contributed, from Day One”.

“Newly arriving EEA [European Economic Area] nationals have a disproportionate impact on the UK,” the report said. “Numbers in employment in the UK grew by nearly 450,000 in the last year. EEA nationals secured about three quarters of that growth in employment, compared to 25 per cent for UK nationals.”

The report says that 60 per cent of Eastern European graduates in the UK end up in lower-skilled jobs, thus forcing out Britons who do not have similar qualifications.