Overnight security was put in place following trespassing at the former Hygrade factory in Westmead Lane, Chippenham, last week.
Chains on the gates were cut with bolt croppers overnight on Tuesday. Nothing appeared to be stolen but police said it was dangerous to enter the site.
The old meat processing factory is due to be demolished later this summer to make way for the construction of retirement flats by developer McCarthy and Stone.
Building work is expected to begin in November.
The company is this week carrying out reports to prepare for the demolition, for which it has conservation area consent.
McCarthy and Stone has planning permission to redevelop the site as 58 assisted living flats for the over 70s, and hopes these will be ready to move into early in 2015.
Along with 33 one-bed and 25 two-bed apartments there are plans for a communal residents’ lounge, function room and serviced restaurant each lunchtime, as well as staff on site to assist day and night.
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