Hospital staff have been attending drop-in sessions to make sure they can spot people from overseas attempting to scrounge free health care.
The sessions started at Hemel Hempstead Hospital, Watford General Hospital and St Albans City Hospital as a reaction to the BBC Panorama documentary that revealed the NHS has lost at least £40 million in four years by failing to identify people travelling from abroad for free health care.
A freedom of information request revealed that in West Hertfordshire between 2008 and 2011 overseas patients have totted up £379,827.75 in outstanding treatment fees, owed to the hospital trust.
From the same period a total of £356,252 has been written off because the trust can’t recover the money.
A spokesman said: “We are doing the drop-in awareness sessions for the next couple of weeks with staff to raise the profile of the Panorama documentary.
“The Overseas Visitors Team is reiterating the hospital policy and making sure staff know what is expected of them.
“The costs of overseas patients are seen as an unnecessary burden on the budget and the Overseas Visitors Team is very active within the trust.”
Anyone who has lived lawfully in the UK for at least 12 months immediately preceding treatment is exempt from charges so in the first instance staff have to ask patients where they have lived for the last 12 months and whether they have the right to live in the UK.