The government has announced that from April this year NHS trusts will be legally obliged to charge overseas patients who are not eligible for free non-urgent or planned care before they receive it.

The new measures also require hospitals and NHS bodies to identify and register a patient's 'chargeable status' so that other parts of the NHS are more easily able to recoup costs from overseas visitors wherever charges apply.

The move comes as the government switches up a gear its drive to recover up to £500 million a year from overseas visitors not eligible for free care, which health secretary Jeremy Hunt claims "can be reinvested in patient care".

"We have no problem with overseas visitors using our NHS - as long as they make a fair contribution, just as the British taxpayer does," he said.

But Dr Mark Porter, chair of the British Medical Association, said "it's hard to see how these new proposals will operate in practice, especially as they are to implemented by law. There is no detail as to how upfront charging will be introduced from scratch in just three months in an NHS already unable to cope with normal operations".

He also cautioned against demonising overseas patients or sowing chaos and confusion within the NHS. "Doctors and nurses cannot be expected to arbitrarily decide whether a patient gets treatment or not," he noted, and stressed that "ministers should not mislead the public into thinking this will result in a cash windfall for the NHS, but must address the wider funding shortfall in the NHS, which has left it understaffed and struggling to care for its patients."

The government's announcement came just days after the Public Accounts Committee said current systems for cost recovery "appear chaotic", and that even taking planned changes to policy and regulation, good practice and IT into account, it is "not convinced that enough is being done to identify and charge overseas patients".

"The government's failure to get a grip on recovering the costs of treating overseas visitors is depriving the NHS of vital funds," said PAC chair Meg Hillier. "We are concerned that financial progress to date does not reflect meaningful progress with implementing the rules and the Department for Health and NHS have much to do if they are to meet their target for cost recovery."

The PAC recommends that the Department of Health publish, by June 2017 at the latest, an action plan setting out specific actions, milestones and performance measures for increasing the amount recovered from overseas visitors, that NHS Improvement should collect and share data on the performance of trusts in charging patients and recovering money, and intervene when performance is clearly falling short, and argues that GPs "could do more to help the NHS increase the amounts recovered".