Hospital trusts need to do more to tackle the problem of foreign patients who avoid paying for NHS care, a senior doctor has said as an investigation revealed millions of pounds were owed for treatment.
Dr Richard Vautrey, deputy chairman of the British Medical Association's GP committee, said trusts must put in place arrangements "that ensure people cannot exploit the system".
His comments came after an investigation revealed almost £40 million could be owed to NHS hospital trusts in England by foreign patients who were not eligible for free care.
Freedom of Information (FoI) requests by Pulse magazine revealed the average unpaid debt for the provision of care to foreign nationals was £230,000 in the 35 trusts which responded.
If this figure was the same across all 168 English acute trusts, the total debt would be almost £40m, the magazine claimed.
The FoI requests showed St George's Healthcare Trust in South London had the largest outstanding debts, totalling £2m from £3.55m invoiced to foreign nationals for health treatment from April 2009.
Barnet and Chase Farm was next, with £488,000 outstanding from invoices worth £934,000.
The Royal Wolverhampton Hospitals Trust collected 24% of the £419,000 owed to it, the figures showed.
A spokesperson for St George's told Pulse: "A high percentage of our patients require life-saving trauma, neuroscience, cardiovascular or paediatric care.
"We're working hard to improve the way we record overseas patients and the debt recovery rate."
Foreign nationals residing in the UK are entitled to free treatment on the NHS, but visitors from outside are expected to either have health insurance or the bill is sent to their country of origin.
Dr Vautrey told the magazine: "Hospital trusts must put in place arrangements that ensure people cannot exploit the system.
"However, we need to be careful that we are not putting barriers in place that prevent people from getting access to healthcare. It can be quite challenging.
"It is too simplistic to call it health tourism. The reality is a lot more complex."
The investigation comes days after campaigners warned GPs had too much freedom to register sick foreigners who may not be entitled to expensive British healthcare.
Migration Watch UK claimed family doctors could decide whether to take on patients without identity documents and give them free treatment which should not be available to them.
The group's chairman Sir Andrew Green said: "To allow such easy and potentially hugely-expensive access without any entitlement must be stopped at once, otherwise the NHS risks becoming the World Health Service."
Last year, FoI requests from Tory MP Chris Skidmore showed £42m in unpaid debts for treatment of foreign patients had been written off by primary care and foundation trusts.