A DERELICT factory in Co Tyrone was targeted by arsonists in two attacks over the weekend.
Herdman's Mill has stood in the village of Sion Mills since 1835.
The first fire was started on Friday evening, causing substantial damage.
A second blaze then caused further damage at around 8.30pm on Saturday.
Police appealed for information.
A spokesman said: "I would also like to advise members of the public that this building has been condemned and under no circumstances should anyone enter the building due to health and safety concerns and a high risk of serious injury."
Herdman's Mill, which once employed more than 1,000 people, ceased spinning linen in 2004.
