A man has been arrested and charged with arson in relation to a large tyre fire in Amberly.
Emergency services were called to the blaze on Racecourse Rd at about 3.10pm.
A police spokesperson said they have arrested and charged a 63-year-old man in relation to the arson.
He was expected to appear in the Christchurch District Court on Saturday.
"Police are not seeking anyone else in relation to this incident however enquiries are continuing."
A public health warning was issued amid concerns of toxic substances billowing into the air during the fire.
The "very, very hot" blaze was at the site of the Amberley tyre stockpile which has been controversial over the years.
Environment Canterbury have been working closely with the Hurunui District Council to ensure the removal of the pile in recent times.
A Herald reporter at the scene said "enormous flames more than 20m high" can be seen as dozens of firefighters battle the raging fire.
Thick black smoke plumes are fanning into the sky.
The fire appears largely contained to the fire area, surrounded by large trees.
The blaze can be heard crackling and sizzling.
The area is surrounded by dry farm paddocks while a stiff southerly breeze fans the fire.
Smoke can be seen from the city, 45km south from Amberley.
One Amberley local come down to watch the dramatic fiery action was frustrated that "this was always going to happen".
"It's a shame that this is the second fire here and the authorities have tried for years to tidy this all up," he said.
"People are pretty upset by it all, especially with all the pollution.
"I think the fire guys will be here for days dealing with this.
"I'm just glad it didn't happen the other day when it was 37C."
Firefighters are thought to be trying to contain it and prevent it spreading to the trees and surrounding paddocks.
"We were first called at about 3.10pm," said a Fire and Emergency New Zealand spokesman.
"Multiple crews from Amberley, Waipara, Woodend, Waikari and Sefton, Rangiora and command unit from Christchurch.
"We are advising nearby residents to keep their windows and doors closed, and to please stay away from the fire site."
FENZ Area Commander Dave Berry said "quite a few thousand tyres" were on fire.
"At the moment becasue of the water table we can't put any water or foam onto the tyres so at this stage we're bgoing to let it burn and protect the exposures," he said.
"It's the smoke that's the effect at the moment... we're just trying to let it burn itself out a bit before we get a digger in to separate the tyres and then we'll bury it."
Berry said there was no indication what caused the fire at this stage.
Fire investigators were on their way to the scene and would speak to the property owner.
Civil Defence and the police were also at the scene.
How long the fire burned for depended on how quickly FENZ could separate and bury the tyres.
"It will be a long night," he said.
"Hopefully she should be down by tomorrow."
However the fire could "possibly" burn for days.
Berry said the fire was so intense due to the fuel loading of the tyres.
"Basically the only difficulty we've got is we can't put this one out, with a scrub fire we could attack it... we're just covering exposures... and letting it burn off," he said.
He described the fire as "very very hot".
It is the second fire at the site in about three years.
A public safey warning has been issued this afternoon by the Canterbury District Health Board's Community and Public Health Unit relating to smoke from the fire.
"Air around this location is smoky and there is potential that people who are sensitive to smoke – such as those with heart or lung conditions, pregnant women, young children and the elderly – may experience symptoms like coughing, shortness of breath or eye, nose and throat irritation," the warning said.
"The main contaminant from fires involving tyres is sulphur dioxide which can cause respiratory problems such as bronchitis, and can irritate your nose, throat and lungs.
"It may cause coughing, wheezing, phlegm and asthma attacks.
"The effects are worse when you are exercising. Sulphur dioxide has been linked to cardiovascular disease."
Canterbury Medical Officer of Health Dr Ramon Pink said exposure to smoke can worsen pre-existing health conditions such as asthma and heart disease.
"People affected by the smoke should close windows and doors, and reduce outdoor exercise," he urged.
"Anyone experiencing health issues from the Racecourse Rd fire should phone their usual general practice team in the first instance.
"After hours you can call your usual practice number 24/7 and follow the instructions to be put through to an nurse for free health advice."
A list of safety warnings was also issued.
"If you see or smell smoke outside, you should stay inside if it's safe to do so," said the DHB.
"Remember to: keep your windows and doors shut, switch your air conditioning to 'recirculate', air out your house when the smoke clears, look out for children, older people, and others at risk."
In December a director of one of the companies which failed to remove the tyres from the site under a court Enforcement Order was sentenced.
Peter Benden was fined $36,000 and required to pay $20,000 toward the costs of removing the tyre pile.
The 19-year-old disappeared without her wallet or mobile phone.