Fly-tippers were responsible for two large gorse blazes that used up hours of Fire Service resources, it has emerged.
There has been a big increase in cases of household waste being illegally dumped in the countryside.
A fire chief said two gorse blazes outside Omagh were a direct result of rubbish dumped on the land being set alight.
Firefighters spent close to a 48-hour period dealing with blazes at Loughmacrory and nearby Mountfield last week. Both fires were started by people igniting waste which had been illegally dumped.
Mark Smyth, area commander with NIFRS's western division, said: "There is a lot of fly-tipping going on at the moment and, while the Environment Agency would know more about this than me, certainly these gorse fires were as a result of rubbish being set alight.
"We have no evidence about who set the fire, whether it was the person who did the fly-tipping or others, and I would imagine they wouldn't have meant it to do what it did, but these fires can very easily get out of control."
Local Sinn Fein councillor Stephen McCann said it illustrated the serious consequences of fly-tipping.
He said: "It is now believed that this massive gorse fire was started by an individual or individuals who had set fire to tyres and other materials that had been fly-tipped.
"The result was the destruction of a wide area of natural habitat and the consequences of this could have been much worse but for the valiant efforts of the Fire Service and local community volunteers to bring it under control.
"Fly-tipping has other serious consequences.
"It can be dangerous to human and animal health, it pollutes land and waterways, is very expensive to clear away and crucially is diverting council resources away from our critical services during this challenging time."
Councils here shut civic amenity sites as part of the coronavirus controls.
Mr McCann continued: "Recycling centres across the north have been closed in line with government advice to stay at home for all but essential journeys.
"Their closure was also to allow for the reconfiguration of services due to reduced staffing levels because of Covid 19, as well as to enable the redeployment of staff to other priority duties.
"So anyone selfishly fly-tipping is not just causing an unsightly blight on the landscape, their actions during this unprecedented public health emergency are nothing short of criminal." In a seven-day period last week the Fire Service dealt with over 100 wildlife fires.
Environment Minister Edwin Poots said anyone detected lighting fires deliberately will be prosecuted.
He said: "Those who show total disregard of the environmental impact on their own communities and countryside should expect the full weight of the law upon them if caught.
"In this time of emergency it can cause significant public health issues and diverts already stretched resources away from other essential services.
"I urge people not to indulge in irresponsible behaviour which can have such a damaging effect on public health and the environment."