Nigel Farage 'concerned' by British government's post-Brexit border plan
It is "of concern" that EU citizens will be able to move freely across the Irish border into the UK without any immigration checks after Brexit, Nigel Farage has said.
The Liberal Democrats also said the proposal "has more holes in it than a colander" and indicated Britain would not reclaim control of its borders.
But the plans were backed by Eurosceptic Tory MPs, who said EU citizens would not be able to work or claim benefits in Britain as a result of the policy.
The British government's position paper on the border says Britain will preserve the Common Travel Area (CTA) between Northern Ireland and the Republic after Brexit, allowing people to enter Britain free from routine border controls.
This is despite the Republic remaining part of the EU and accepting the free movement of citizens from the bloc.
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The British government said it is "confident" it can still enforce new immigration controls on EU citizens without a hard border with the Republic, through checks on things such as the jobs market and welfare system.
Former Ukip leader Mr Farage told the Press Association: "Once again the UK Government is bowing to EU demands.
"The operation of the land border between the north and south should be none of their business.
"That the government would willingly allow EU nationals to freely move into UK territory is of concern."
Ed Davey, a Liberal Democrat former cabinet minister, added: "The Brexiteers claimed it was worth damaging the UK economy to reclaim control of our borders, now we're told even this isn't going to happen.
"The Conservatives are finally admitting that there are ways to control free movement by making reforms to our labour market and social security.
"That raises the question, why are they still planning to damage jobs and living standards by leaving the single market?"
Conservative MPs Andrew Bridgen and John Redwood both told the Press Association they supported the measure.
"The main way the government is likely to enforce a new migration policy is through work permits for EU citizens from the continent, whether they enter direct or via the Republic of Ireland," Mr Redwood said.
"The aim is to keep current UK/Republic of Ireland arrangements.
"The paper is quite clear that we can carry on with the current Common Travel Area and citizenship arrangements between UK and the Republic of Ireland, whilst imposing controls on continental EU nationals seeking work in the UK."
Mr Bridgen added that there had been a free travel arrangement between the UK and Ireland since 1922 and he was perfectly happy for people from the EU to keep coming to Britain.
"What they won't be able to do is work or claim benefits," he added.
Officials say the UK has an ongoing programme of security cooperation with the Irish government, while Ireland is not a member of the Schengen free movement area, meaning passports of EU citizens are checked as they enter the country.
The position paper says: "When considering the nature of the CTA as a border-free zone, it is important to note that immigration controls are not, and never have been, solely about the ability to prevent and control entry at the UK's physical border.
"Along with many other member states, controlling access to the labour market and social security have long formed an integral part of the UK's immigration system.
"The nature of this range of control mechanisms means that the UK is confident that it will be able to: maintain existing movement to the UK from within the CTA without requiring border controls, as now; respect Ireland's ongoing EU free movement obligations; and put in place a new UK immigration system and controls for EEA (European Economic Area) citizens."
The British government is due to unveil further details about its immigration policy in the autumn.
The position paper says Britain believes an agreement on maintaining the CTA can be agreed in the first phase of its negotiations with the EU.
Other parts of the document raise issues about what impact customs arrangements on the Irish border could have on Britain's ability to strike new trade deals.
One passage talks about future "regulatory equivalence on agri-food measures", where the UK and EU agree to the same standards, albeit with some flexibility.
Britain's animal welfare standards have been a major talking point, as after Brexit it does not have to comply with EU rules.
This has been highlighted over chlorine-washed chicken, which is banned by the EU but not in the US - and could form part of a future trade deal.