Up to 30 gorse fires are raging across the country, with the most serious at a Coillte forest in Co Galway now declared a threat to homes and wildlife habitats.
Most of the fires are around the Border area and in Roscommon and Sligo. The most significant is in Cloosh Valley, Galway, which has decimated about 3,500 hectares of forest and bog land.
The 4,000 hectare forest is one of the largest in Ireland, and firefighters are battling to bring it under control after conditions worsened on Tuesday.
In a statement Coillte said despite some respite during the morning, the fire “escalated this afternoon as high winds and warm temperatures combined”, spreading it beyond Coillte-owned land.
“The forest fire at Cloosh is also threatening the welfare of many homes and local communities, as well as causing devastation to vast areas of wildlife habitat,” it said.
Gerard Murphy, managing director of Coillte Forest, said: "The Cloosh fire is a massive one, the biggest one I've seen in the many years that I've been involved."
A regional emergency response operation comprising Coillte staff, the fire service, Army personnel and helicopters is now in place.
There have been more than 100 serious gorse and forest fires in recent weeks, partly due to a prolonged dry spell since the beginning of April and average rainfall at 25 per cent of normal levels for this time of year.
Mr Murphy said he believed most had been started deliberately either through the burning of vegetation or maliciously.“I’m quite confident to say that most of them are deliberate.”
Minister for Agriculture Michael Creed and Minister for Rural Affairs Heather Humphreys issued a joint statement reminding the public it was an offence under the Wildlife Act to burn vegetation between March and August.
“There is a huge cost to this reckless behaviour, not just to physical property but also the cost of disruption to normal emergency services operations,” Ms Humphreys said.
Galway county councillor Tom Welby said some members of the public were putting the safety of themselves and firefighters at risk by trying to get a closer view.