DETECTIVES have launched an arson probe after a major fire at the derelict Herdman’s Mill in Sion Mills.
The Fire and Rescue Service say.shortly after 9 pm on Sunday night.
Twenty-two firefighters from Derry, Strabane, Castlederg and Newtownstewart fought the flames.
The operation ended at midnight.
The building has been “significantly damaged by the fire”, said NIFRS western commander Mark Deeney.
There have been a series of arson attacks at the site in recent year.
There were two fires within a number of days in June.
Aerial equipment was used to bring the fire under control on Sunday night
The former linen mill dates back to 1835 and was owned by the Herdman family for more than 170 years.
It once employed more than 1,000 people but it closed as a working mill in 2004.
Ten years later, the derelict site was bought by County Tyrone lottery winner Margaret Loughrey from Strabane.
She is said to have paid £1 million for the site.
Loughrey bought just months after she won £27 million in the Euromillions jackpot in December 2013.