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”.