An NHS trust that refused some surgery to obese people plans to ban staff from smoking while wearing a uniform or ID badge - including when off-duty.
Suffolk East Primary Care Trusts' (PCT) combined board is being asked to approve a new smoking policy when it meets on Wednesday.
A trust spokeswoman said the draft plan was part of a government directive and Suffolk PCT was being "transparent".
Public service union Unison said the plan is "unworkable".
The policy would apply to all staff, volunteers, patients, visitors and contractors.
The policy says staff should not smoke when visiting other premises, even if the rules applied there allow smoking.
Smoking would not be allowed in the trust's leased and pool cars, except where the driver contributes to the lease cost for personal use of the vehicle.
The trust claims 80% of staff support the ban.
A spokeswoman for the trust said: "Many trusts have introduced a smoke-free policy but we have chosen to be more transparent."
If approved, the policy would be introduced in March to correspond with No Smoking Day.
A trust spokeswoman said: "The delay in introduction will allow staff to take advantage of stop smoking clinics."
Legal action threat
Unison spokesman Ian Talbot warned that the move could force smokers underground, causing health and safety risks.
"We're not against a smoking ban, but when staff are dictated to this in this manner it is an infringement on their civil liberties and completely untenable," he said.
"The unions were not consulted on this policy and if is approved our legal department will be looking into the issue."
Earlier this month, three Suffolk primary care trusts came under fire after ruling that patients with a body mass index (BMI) over 30 will not get operations like hip and knee replacements.