Police have issued a warning in advance of the potentially unprecedented heatwave coming to the UK after a series of wildfires on moorland near Manchester which they now believe were started deliberately.

The blaze began last weekend and swept across part of Saddleworth Moor near a car park close to the Dovestone reservoir.

On Saturday, Greater Manchester police (GMP) said a joint investigation with Greater Manchester fire and rescue service (GMFRS) has, so far, established that there were five seats of fire with traces of accelerant found at three of the seats.

Supt Phillip Hutchinson, of GMP Oldham district, said there is a public space protection order in place at Saddleworth Moor and it is a criminal offence to start fires in the area including barbecues. A breach of the order can result in a £1,000 fine.

“Inquiries are ongoing to identify those responsible for starting these fires which could have had a devastating impact on the land, the wildlife and residents who live in the surrounding area. I ask anyone with information to share it with us as soon as possible.

“Only days before this fire, we attended an event during which we spoke with members of the public about how to use the area in the summer. Unfortunately, during this event, our officers sighted persons posing a risk so three fixed-penalty notices were issued.

“I ask members of the public who frequent the area and residents who live surrounding it to report anyone they suspect of planning an illegal barbecue or committing any other crime.”

Jim Wilmott, GMFRS group manager at Bury, Oldham and Rochdale, said: “It’s difficult to understand why anyone would want to deliberately start a fire in moorlands, but sadly it does happen and when conditions are this dry, they grow quickly and easily out of control.

“For those who do think this is a good idea, you should know that not only does it destroy precious moorland, but it also puts local wildlife and people at danger, causing huge disruption and means our resources are often unable to attend other serious incidents.”

Anyone with information should contact GMP or the independent charity Crimestoppers on 0800 555 111.

Emergency services across the country have highlighted cases of fires being started by arsonists in recent days.

Derbyshire fire and rescue service said on Friday that in a seven-day period they were called out to tackle 66 fires in the open and urged the public to discard their rubbish responsibly, not to barbecue in open spaces and not to start blazes.

Essex County fire and rescue service said almost a hectare (two acres) of woodland and undergrowth were damaged by the second blaze in a week on Friday which they concluded was started deliberately.

On Facebook, a spokesperson for the fire service said: “Two acres of woodland and undergrowth in Heybridge have been damaged following a fire. The cause of the fire has been recorded as deliberate.”

Essex County fire and rescue service said it typically sees an increase in deliberate fires during summer months.

It added: “You can help us to prevent them by getting in touch with FireStoppers. Managed by CrimeStoppers, FireStoppers is an anonymous way to report what you know about deliberate fire setting in your area.

“It’s not for reporting any blame, it’s for us to prevent the fires from happening.”

Norfolk fire and rescue service also urged the public to be vigilant and report any suspicious behaviour to police.