The military has been called in to help battle the moorland fire that has engulfed swathes of land in Greater Manchester on the hottest day of the year so far.

Authorities declared the inferno on Saddleworth Moor a “major incident” as plumes of smoke from multiple blazes covered the sky. Some 34 homes were evacuated on Tuesday night as the flames – in some cases reportedly up to 20ft high – crept closer.

Greater Manchester Fire and Rescue Service (GMFRS) said that at one stage the blaze covered a 6km area. More than 100 firefighters are now engaged in tackling the fire but senior officers said they had not yet discovered the cause.

While the fire started on Sunday and was initially brought under control, it was reignited on Monday by the hot weather and then spread throughout the course of Tuesday.

Dave Keelan, GMFRS’s assistant chief fire officer, said on Wednesday afternoon: “We have been liaising with a military adviser on the scene and following those discussions we have requested military assistance from the Ministry of Defence.

“There’s still a lot of smoke from the fire but air quality levels are being monitored regularly in different locations. Air quality is currently at a safe level and therefore residents have been let back into their homes.

“We don’t know the cause of this incident at this stage and it would be very difficult to ascertain the cause due to the extent of the damage but we will be looking into that once we have tackled the fire.”

Two helicopters, one from Greater Manchester Police and the other from United Utilities, have been deployed, with the latter capable of dropping water on parts of the fire that are difficult to reach on foot.

The decision to call in the army came as Wednesday officially became the hottest day of the year so far, with a temperature of 31.9C recorded in Wales amid a days-long heatwave.

The Met Office warned that temperatures were still rising, meaning the record could be broken again within the next 24 hours.

Saddleworth Moor fire: Greater Manchester blaze in pictures Show all 34 1 /34 Saddleworth Moor fire: Greater Manchester blaze in pictures Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Thursday June 28, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Danny Lawson/PA Wire Danny Lawson PA Saddleworth Moor fire: Greater Manchester blaze in pictures British Army soldiers of 4 Scots assist the fire fighters on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures British Army soldiers of 4 Scots assisting fire fighters EPA/Ministry of Defence Saddleworth Moor fire: Greater Manchester blaze in pictures A firefighter tackles the wildfire on Saddleworth Moor which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Thursday June 28, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Danny Lawson/PA Wire Danny Lawson PA Saddleworth Moor fire: Greater Manchester blaze in pictures Soldiers douse the wildfire AFP/Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures A helicopter fills a container with water from Upper Swineshaw Reservoir AFP/Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures Members of the 4th Battalion, Royal Regiment of Scotland join firefighters AFP/Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Thursday June 28, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Danny Lawson/PA Wire Danny Lawson PA Saddleworth Moor fire: Greater Manchester blaze in pictures A firefighter tackles the wildfire on Saddleworth Moor which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Thursday June 28, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Danny Lawson/PA Wire Danny Lawson PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Thursday June 28, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Danny Lawson/PA Wire Danny Lawson PA Saddleworth Moor fire: Greater Manchester blaze in pictures The full moon rises behind burning moorland between Dovestones and Buckton Vale Getty Saddleworth Moor fire: Greater Manchester blaze in pictures These dramatic pictures taken on Monday evening show the fire on Saddleworth Moor taking hold and sending huge plumes into the sky. See National story NNMOOR; A major incident has been declared after a huge moorland fire forced dozens of residents to flee their homes in Greater Manchester. The army is on standby to help tackle the blaze which has been raging for several days on Saddleworth Moor. Some 34 properties have been evacuated in Carrbrook, Stalybridge, while police have confirmed some nearby schools will be closed. Public Health England has urged residents to keep windows and doors shut as smoke and flames could be seen for miles. Kate MacRae / SWNS.com Kate MacRae / SWNS.com Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA Saddleworth Moor fire: Greater Manchester blaze in pictures A PCSO assists a member of the public with face mask to protect gainst the smoke on Calico Crescent, Stalybridge near to the wildfire on Saddleworth Moor. PRESS ASSOCIATION Photo. Picture date: Wednesday June 27, 2018. The fire continues to spread after the blaze was declared a major incident by Greater Manchester Police. See PA story FIRE Saddleworth. Photo credit should read: Peter Byrne/PA Wire Peter Byrne PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters on Saddleworth Moor attempt to dampen down the area to stop the spread of fire after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Wednesday June 27, 2018. The fire started on Sunday and reignited the next day amid Britain's heatwave and has devastated land around Carrbrook. See PA story FIRE Saddleworth. Photo credit should read: Peter Byrne/PA Wire Peter Byrne PA Saddleworth Moor fire: Greater Manchester blaze in pictures STALYBRIDGE, ENGLAND - JUNE 27: Fire fighters continue to tackle a large wildfire sweeping across the moors between Dovestones and Buckton Vale in Stalybridge, Greater Manchester on June 27, 2018 in Stalybridge, England. Firefighters have declared a 'major incident' as they battle the huge moorland fire which measures 6km. (Photo by Anthony Devlin/Getty Images) Anthony Devlin Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures STALYBRIDGE, ENGLAND - JUNE 27: Fire officers continue to fight a large wildfire on the moors above Stalybridge, Greater Manchester on June 27, 2018 in Stalybridge, England. Firefighters have declared a 'major incident' as they battle the huge moorland fire which measures 6km. (Photo by Anthony Devlin/Getty Images) Anthony Devlin Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Mayor of Greater Manchester Andy Burnham speaks to the media, as firefighters tackle a wildfire on Saddleworth Moor, which continues to spread after the blaze was declared a major incident by Greater Manchester Police. PRESS ASSOCIATION Photo. Picture date: Wednesday June 27, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Peter Byrne/PA Wire Peter Byrne PA Saddleworth Moor fire: Greater Manchester blaze in pictures **FREE EDITORIAL USAGE** Aerial view of the fire on Saddleworth Moor. See National story NNMOOR; A major incident has been declared after a huge moorland fire forced dozens of residents to flee their homes in Greater Manchester. The army is on standby to help tackle the blaze which has been raging for several days on Saddleworth Moor. Some 34 properties have been evacuated in Carrbrook, Stalybridge, while police have confirmed some nearby schools will be closed. Public Health England has urged residents to keep windows and doors shut as smoke and flames could be seen for miles. SWNS.com SWNS.com Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters take a break from tackling the wildfire on Saddleworth Moor. PRESS ASSOCIATION Photo. Picture date: Wednesday June 27, 2018. The fire started on Sunday and reignited the next day amid a heatwave. See PA story FIRE Saddleworth. Photo credit should read: Peter Byrne/PA Wire Peter Byrne PA Saddleworth Moor fire: Greater Manchester blaze in pictures Fire officers continue to fight the large wildfire Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Fires on Saddleworth Moor Sean Quarmby/PA Saddleworth Moor fire: Greater Manchester blaze in pictures Fire officers continue to fight a large wildfire on the moors above Stalybridge Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Fire officers outside Castle Farm Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Horses are moved through heavy smoke in Carrbrook Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures A scorched fencepost Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Handout photo from Sean Quarmby of fires on Saddleworth Moor on Tuesday night. PRESS ASSOCIATION Photo. Issue date: Wednesday June 27, 2018. A number of homes have been evacuated as fires on Saddleworth Moor continue to spread. See PA story WEATHER Hot Fires. Photo credit should read: Sean Quarmby/PA Wire NOTE TO EDITORS: This handout photo may only be used in for editorial reporting purposes for the contemporaneous illustration of events, things or the people in the image or facts mentioned in the caption. Reuse of the picture may require further permission from the copyright holder. Sean Quarmby Sean Quarmby/PA Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters on Saddleworth Moor attempt to dampen down the area to stop the spread of fire PA Saddleworth Moor fire: Greater Manchester blaze in pictures A llama sits in a field below burning moorland Getty Images Saddleworth Moor fire: Greater Manchester blaze in pictures Firefighters tackle the wildfire on Saddleworth Moor PA

Thirty-four homes in Carrbrook have been evacuated as a precaution but there are no reported injuries.

Four schools were also closed on Wednesday – Mossley Hollins High School, Buckton Vale Primary School, Millbrook Primary School and St Raphael’s Catholic Primary School.

Anthony Leach, who lives in the area, said the smell of smoke was “in every room”.

He said: “It’s like you could almost smoke mackerel in there.”

Firefighters from Cheshire and Derbyshire have been supporting those from Greater Manchester.

Public Health England has released a warning to any people who may have been affected by smoke and residents have been recommended to close their windows and doors with some streets covered in ash.

Asthmatics were advised to stay inside their homes and people were warned to also keep pets indoors.

“Fire crews have been working in tremendously difficult conditions, in the heat and the smoke,” Leon Parkes, assistant chief fire officer for GMFRS, said at a press conference.

“We’ve been working with our partner agencies to deal with the situation. The situation is evolving and last night the decision was made to pull a multi-agency meeting and declare a major incident on the basis that there was partner agency working required.

“A number of actions were put in place, including the evacuation of some nearby houses, because of the spread of the fire.”

Saddleworth Moor fire rages in timelapse video

He added that some of the fire scenes were two miles away from where fire engines could park and other vehicles were being used to get firefighters and kit into those areas.

Firefighter Ricky Case, who has been out on the moors working to tackle the fire, said: “It’s just the sheer vastness of it. It’s one of the biggest ones I’ve been on in a long time. The logistics of it all, trying to get water to the locations where we need it.”

Reverend Chris Finney has opened the doors of his church, St James in Millbrook, to anyone who requires support.

He said: “I’m about a mile away from Calico Crescent [where homes have been evacuated]. I’ve lived in this area all my life and I think I can say that within my memory – and I’m in my sixties – I’ve not seen fires on the moors to the extent that we’re looking at them at the moment.”

Andy Burnham, Greater Manchester’s mayor, paid tribute to the firefighters.

The force said anyone who is in need of a safe place to stay should contact Tameside Council.