New measures introduced by the UK government in April linking applications for residence permits to up-front payments for potential use of NHS hospital services, and proposals to further restrict access to NHS services for migrants, will not reduce the strain on NHS resources - and may end up costing more in the long run.

The UK is proud of its socialized approach to health care but it has increasingly become unsustainable so government is seeking ways to limit access to people, or get them to chip in for costs. The newly implemented policy imposes an up-front surcharge of £200 ($310) per year to guarantee access to NHS hospital care for people from outside the European Economic Area when they submit an application to work, study, or visit their families in the UK for a period of longer than six months - or when they are applying to extend their visas.

Those who cannot pay will automatically have their application rejected. Writing in The BMJ this week, Lilana Keith and Ewout van Ginneken say such policies are "shortsighted and misleading."

Some applicants do not need to pay the surcharge, such as asylum seekers and victims of human trafficking, but not all vulnerable groups of migrants are protected from these charges.

They include some illegal immigrants. The surcharge will push people into irregularity and prevent some undocumented migrants with a right to reside in the UK from being able to regularise their residence, they warn.

"This policy alone makes the UK an outlier in Europe," they write. No other EU country has such a structural link between immigration applications and access to health services.

The government is also considering charging undocumented migrants for emergency and primary services which are currently provided free of charge.

"The UK government wants the public to believe that the changes being proposed will make the country less appealing to undocumented migrants and will save taxpayers' money.

This view is shortsighted and misleading," say the authors. For example, not having access to preventive services may lead to outbreaks, with subsequent costs to the health system and wider society. Restricting access to services based on residence status also requires complex administration, itself a major burden on the NHS.

The authors argue that the estimated 618,000 undocumented migrants living in the UK contribute to the economy and that denying access "may end up costing the NHS more in the long run."

"The UK government is wrong to assume that charging migrants for access to health services will strongly reduce the strain on NHS resources," they write. The restrictions have several negative knock-on effects, as well as causing direct harm to the health and wellbeing of vulnerable people.

"Rather than holding a public consultation on extending charging to emergency and primary care, as the freshly elected Conservative government plans to do, the evidence indicates that the opposite approach would serve the UK and its NHS better. They should explore ways to provide non-discriminatory access to the NHS for all," they conclude.