Most gorse fires 'started deliberately'
At least 80% of the 302 gorse fires in Northern Ireland over the weekend were started deliberately, fire officials say.
There have been 498 gorse fires across the region since the start of May.
The Cuilcagh Mountain trail in County Fermanagh has been closed to the public due to one of the fires.
Those who started fires deliberately put firefighters, the public and property at risk, said the Northern Ireland Fire and Rescue Service.
The fire service was moving its engines around the country to keep the public safe and was appealing for their help, said NIFRS Group Commander Brian Stanfield.
He described the fire phenomenon as "complete madness, it's just reckless anti-social behaviour".
"We're appealing to the public. If you do know people who are fire setting, let the PSNI know so we can put them through the courts because this is absolutely ridiculous," he said.
How to prevent fires in countryside
- Make sure cigarettes and other smoking materials are fully extinguished
- Never leave barbeques unattended and make sure they are fully extinguished before disposing of contents
- Avoid lighting fires in open countryside
- Do not leave bottles or glass in woodlands
Fire crews have been working since Sunday to bring a gorse fire near Fivemiletown, County Tyrone, under control.
The fire service said it covers an extensive area at Mullaghfad forest on the Tyrone and Fermanagh border.
"We had eight fire appliances at the incident in Fivemiletown and we're also working with the forestry both north and south of the border and the Southern fire service as well to bring that fire under control," he said.
"That fire started at 11:00 BST on Sunday and we still have two appliances up on that mountain in very difficult terrain, trying to bring that under control.
BBC News NI's environment correspondent, Conor Macauley, at the scene
Dozens of personnel are involved.
Specialist equipment, including tanker lorries bringing water to the site, have been deployed.
It's the second day the fire service has been on site.
Much of the effort involves fire crews using beaters to put out the flames.
It's understood the fire may have been started in a number of different locations.
Mullaghfad is part of a large forest area which includes Crocknagrally, Jenkin and Fardross forests.
The forest is located within a Special Protection Area for hen harriers and is partly made up by the Slieve Beagh Area of special scientific interest.
"We also had six fire appliances at another incident in Cookstown at the same time."
Mr Stanfield said gorse fires were "resource intensive" and said crews were prepared to deal with any further incidents this week.
"There's a high risk, the countryside is like a tinder box and our resources will be stretched if people continue at this rate to light fires," he warned.
He said people were unaware of the personal risks when they committed such acts.
"When the ground is that dry and there's a change in wind direction, the fire will move faster than the person can run and it's only a matter of time until someone is seriously injured or killed at one of these fires," he added.