More than £24,000 is owed to Airedale NHS Foundation Trust by foreign patients who have failed to pay their bills after treatment, it has been revealed.

And almost £600,000 is owed to Bradford Hospitals Trust, a Freedom of Information request has shown.

A detailed response from Airedale shows invoices totalling £112,536 were issued in a five-year period, and £50,784 was paid. Twelve patients had their bills written off to a combined total of £37,263 and the hospital is seeking payment from ten patients totalling £24,489.

A spokesman for Airedale NHS Foundation Trust said: “In the majority of cases these costs relate to providing urgent and emergency care. Under Department of Health guidelines, we have a duty of care and are required to treat these cases. We are taking every measure possible to try to recover this amount that we are owed.”

Unless their country has a reciprocal arrangement with the UK, foreign nationals are required to pay for any non-emergency NHS treatment they receive.

But in many cases, recovering the debts proves impossible, and it is estimated that the NHS is owed £40 million across the country, with a total of £14 million written off by health trusts last year.

Chris Skidmore, the Tory MP who compiled the figures, is campaigning to change the law so that more can be done to secure payment before treatment starts.

He said: “The NHS is a national health service, not an international one.”

Recently ministers have said they are determined to reduce the amount of debt being written off. With the cost of treatments rising along with patient numbers, there has been a steady increase in the amount of cash owed to the trusts by foreign nationals.

Hospital trusts in London tended to have the largest debt from foreign patients, with one writing off more than £1 million alone last year.

Robert Oxley, campaign manager of the TaxPayers’ Alliance, said: “No one should be denied emergency treatment but with NHS budgets already stretched we cannot afford to bankroll an international health service.

“It is UK taxpayers who are left picking up the tab when foreign nationals don’t pay their bills. More must be done to ensure they aren’t able to shirk their responsibilities. Those who aren’t eligible for free care and who are in no need of urgent care should not be treated at taxpayers’ expense.”