The Mournes wildfires took hold on the same weekend that the first wildfire warning of the year was issued following a prolonged spell of dry weather.
On Monday, a Mourne Mountain Rescue team co-ordinator said the challenge with recurring wildfires is that “there are no consequences” for those responsible.
Martin McMullan said the fires in the mountains at the weekend “definitely didn’t look like they started from a recreational source”.
Andrew Muir, the environment minister, rejected claims of no consequences and said arsonists could face prison in some cases, but he added that the authorities need the public’s help to bring them to justice.
Muir was asked if areas vulnerable to wildfires should be patrolled at this time of year to prevent future arson attacks.
“The Mournes and many other areas across Northern Ireland, including, for example the Sperrins, are very large geographic areas and we can’t have individuals everywhere,” Muir replied.
The minister said he had spoken to the Police Service of Northern Ireland (PSNI) and they had “issued a statement making it very clear that they will carry out investigations around this”.
Last week, the Mourne Heritage Trust charity expressed concern about the loss of “engagement rangers” in the Mourne Mountains.
The roles were introduced in response to record visitor numbers in the Mournes during the Covid pandemic.
However, a lack of funding saw the number of those roles reduced, with the last engagement ranger leaving his post in December.
Meanwhile, the Department of Agriculture, Environment, and Rural Affairs published its wildfire action, external earlier this month.
It set out a coordinated response to what officials described as a growing threat.
It includes dozens of measures aimed at improving resilience and reducing the frequency and severity of fires.