Former London Mayor Boris Johnson and other leading voices calling for Britain to leave the European Union say the numbers of people moving to the UK are putting too much of a strain on public services.
They argue that the country needs a way of deciding who is allowed to move to the UK which is "fairer, more humane and better for the economy."
The free movement of people -- and goods, services and capital -- is a guiding principle of the EU.
But Johnson and fellow Conservatives Michael Gove and Priti Patel, along with Labour's Gisela Stuart, say EU membership means Britain cannot control who comes to the country.
"Class sizes will rise and [hospital] waiting lists will lengthen if we don't tackle free movement," the four say in a joint statement released Wednesday
"If we vote to remain in the EU then continued free movement for jobseekers will place considerable pressure on the wages of low paid British workers," they add.
One in eight people in Britain were born abroad, 48% of them in the EU, according to the Office for National Statistics
In mid-2014, the ONS says, there were an estimated 3.03 million people born in other EU countries living in the UK.
Many Britons have also moved to live and work elsewhere in the EU: according to ONS estimates, 1.79 million British migrants live across the continent.
The Vote Leave team say they would introduce an "Australian-style points based system
" -- already used to control the numbers of non-EU migrants coming to the UK -- to select who gets to move to Britain.
If the UK votes to leave the EU in the referendum on June 23, they say that by the next election (currently planned for 2020):
- the automatic right of all EU citizens to move to the UK to live and work will end
- a points-based system will help decide who is allowed in
- those coming to the UK to study or work will be admitted on the basis of their skills
- "for relevant jobs ... all those who come have the ability to speak good English"
Vote Leave says that in the event of a Brexit, EU citizens already lawfully resident in the UK would automatically be given indefinite leave to remain.
Irish citizens' rights to enter, live and work in the UK would be unchanged, the group says.
The "Stronger In
" campaign insists that a vote to leave the EU would not stop immigration or prevent people from Europe moving to the UK
It says "countries such as Norway and Switzerland, who are not part of the EU, have to accept free movement and have higher rates of EU migration than the UK."
Reaction to the plan was mixed on the streets of London Wednesday.
"I think it will match the requirements of the economy with the people coming in, so I think it's a good idea," pastoral worker Kath Adkins, 54, told CNN.
"There are loads of people coming in and it is impacting every service, from education to medical and we are struggling," said IT specialist Priyanka Agrawal, 35.
"I think it's important that we control immigration but I don't think that we should leave the EU," said James Griffin, 34, who works in hospitality.
"Freedom of movement is great -- I work with Eastern Europeans who are ... a lot more determined and better workers than many of the British people I work with."