Two large-scale moorland fires in England have merged to create a major incident near Bolton in Greater Manchester, British police said on Saturday.
The fires on Winter Hill and Scout Road, near Bolton, have merged, with pedestrians and motorists urged to stay away from the area.
Firefighters worked through the night, and the fire service said "full firefighting operations" resumed.
Brigades further afield, including from Walsall, Nottingham and Warwickshire, have also joined the effort on Sunday morning.
Area manager Ben Levy said that a presence had been maintained overnight at both sites. "As dawn broke we headed back onto the hilltops for another day battling both incidents."
On Saturday night, he said "good progress" has been made.
He said: "It's been a long and demanding day with challenging moorland fires plus other incidents facing the Fire Service. I am so proud of our hardworking firefighters and Control staff."
Appealing to the public to keep their distance, Lancashire Fire and Rescue Service said in a post on Twitter they "appreciate" the offers of help but are "really concerned that members of the public are heading up on to the moors".
"Keeping windows and doors closed due to the smoke is also advised. Thank you," the fire service added.
Greater Manchester Fire and Rescue Service said it had 28 fire engines tackling the moorland fires.
There are about 120 personnel on the moors, split between seven areas of wildfire in Tameside and Winter Hill, Bolton.
Assistant chief fire officer Dave Keelan said: "This is an exceptionally challenging time and I am proud of the hard work and brave commitment of our firefighters."
Lancashire fire service area manager Tony Cook said "very intensive firefighting" is taking place on Winter Hill, including personnel doing shuttle runs in appliances to get water to the scene while others manually try to beat the fire out.
Fire break trenches are also being dug to try and protect local buildings.
He told Rock FM News the blaze is now considered "a major fire with substantial consequences", adding: "For us, one of the major issues is the strategic infrastructure of Winter Hill radio mast, so we need to protect them."
Several roads in the area have been closed.
This latest development comes after the U.K. government was asked on Friday to extend the military deployment helping fight wildfires on Saddleworth moor for another three days, as fire chiefs record their busiest week in history.
Greater Manchester mayor Andy Burnham said he had asked the Ministry of Defence to extend the deployment of a 100-strong group of soldiers from the 4th Battalion, Royal Regiment of Scotland, who joined the fight on Thursday, initially for 48 hours.
Meanwhile, residents living near Saddleworth Moor have reported health fears including bleeding noses, eye irritation and chest problems.