The NHS will ban patients from surgery indefinitely unless they lose weight or quit smoking, under controversial plans drawn up in Hertfordshire.

The restrictions - thought to be the most extreme yet to be introduced by health services - immediately came under attack from the Royal College of Surgeons.

Its vice president called for an “urgent rethink” of policies which he said were “discriminatory” and went against the fundamental principles of the NHS.

In recent years, a number of areas have introduced delays for such patients - with some told operations will be put back for months, during which time they are expected to try to lose weight or stop smoking.

But the new rules, drawn up by clinical commissioning groups (CCGs) in Hertfordshire, say that obese patients “will not get non-urgent surgery until they reduce their weight” at all, unless the circumstances are exceptional.

The criteria also mean smokers will only be referred for operations if they have stopped smoking for at least eight weeks, with such patients breathalysed before referral.

East and North Hertfordshire CCG and Herts Valleys said the plans aimed to encourage people “to take more responsibility for their own health and wellbeing, wherever possible, freeing up limited NHS resources for priority treatment”.

Both are in financial difficulty, and between them seeking to save £68m during this financial year.

Ian Eardley, senior vice president of the Royal College of Surgeons, said it was wrong to bar NHS treatment to any group of patients.

“Singling out patients in this way goes against the principles of the NHS,” he said.

"This goes against clinical guidance and leaves patients waiting long periods of time in pain and discomfort. It can even lead to worse outcomes following surgery in some cases,” he said.

"There is simply no justification for these policies, and we urge all clinical commissioning groups (CCGs) to urgently reverse these discriminatory measures."

The senior surgeon said he was concerned that the latest rules were the “tip of the iceberg”.

And he raised concern about the fact such policies meant patients were refused a referral without even seeing the specialist who should take such decisions.