Prison guards have been threatened with "the bash" when the ban on inmates smoking takes effect in a year, says the guards' union.
President Beven Hanlon says the ban will put guards and staff such as tutors who remain smokers in danger from prisoners.
"Not just prisoners who get frustrated at smelling fresh smoke on you and just lash out, but because you are introducing an item that is suddenly a high-priority contraband item.
"The prisoners will do anything to get hold of it."
He said staff from around the country had phoned him yesterday to report prisoners saying, "If you guys are going to get rid of smoking, you are going to get the bash. We'll just take it out on you."
Mr Hanlon said he was threatened at Hawkes Bay Prison yesterday by two prisoners who identified him as someone who had talked about the issue on television.
"They were saying, 'We'll punch you in the head'."
Corrections staff will be encouraged to give up smoking, but will be allowed to smoke in designated areas - although not near prisoners.
About two-thirds of prisoners - or 5700 - smoke.
They are allowed to do so in their cells and designated outdoor areas.
They will get a year and some support - such as nicotine patches - to knock off before the ban takes effect in July 2011.
Corrections Minister Judith Collins cited health and safety dangers to prison staff from second-hand smoke and the possibility of legal action for the ban.
She initially suggested allowing smoking in restricted areas - some Australian prisons allow it outdoors - but the Corrections Department rejected that option.
Chief executive Barry Matthews said one of the main reasons was that smoking outside would still require prisoners to hold cigarette lighters, which could lead to fire damage.
He showed photographs of cells and bedding damaged by lighters.
In Australia, these and matches are banned in most prisons and inmates light cigarettes from a device bolted to an outdoor courtyard wall.
Neither Mrs Collins nor Mr Matthews has smoked, but the minister said she grew up being subjected to second-hand smoke.
Former prison superintendent Celia Lashlie said the ban would create havoc, but Whangarei Mayor Stan Semenoff, who has been pushing for the move, said crime rates could drop.
A smoking ban at a prison on Britain's Isle of Man had become a deterrent for reforming criminals who couldn't face prison terms without tobacco, Mr Semenoff said.
The drop in crime has been reported by British media, including the Daily Telegraph, which said the crime rate on the island had fallen by 14 per cent and burglary by 35 per cent.
"It's like they are more scared about giving up smoking than a criminal record and time in the nick," a police source told the newspaper.
Since becoming Corrections Minister in November 2008, Mrs Collins has cracked down in prisons.
She has banned prisoners holding personal razor blades, which were fashioned into weapons - for example, by melting toothbrushes with cigarette lighters for use as handles.
Mr Hanlon said other measures had made prisoners agitated.
There were no replacement staff when officers were sick, for example. Instead more prisoners were kept locked up, to keep up the ratios.
"This could just be another straw to break the camel's back."
Mr Hanlon guessed about half the country's 3260 prison guards smoke.