A politican has spoken of his bitter disappointment following another suspected arson attack on Herdman's Mill in Sion Mills.
West Tyrone SDLP MLA Daniel McCrossan called on public authorities to intervene to protect the historic site.
The blaze started yesterday evening before being extinguished by firefighters.
In 2014, Herdman's Mill was bought by Strabane woman Margaret Loughrey for £1m after she won almost £27m in the Euromillions lottery draw.
The Mill had been seriously damaged in several previous arson attacks.
"It is bitterly disappointing to learn of yet another fire at the Herdman's site. This is a hugely important and historical site in Tyrone which has been subjected to a spate of arson attacks in the last few years," Mr McCrossan said.
"The people of Sion Mills and the wider area are fed up with the Mill being left in ruins and are upset that a large piece of their history has literally gone up in flames.
"If action is not taken, I fear there will literally be nothing left of the Mill and the history attributed to it."
It came hours after a one kilometre-wide gorse fire broke out in Co Antrim.
Eight fire appliances and 48 firefighters were battling the blaze on land near Craig's Forest, Finvoy in Ballymoney, the NIFRS said.
Firefighting operations were expected to continue well into last night.