Builders carrying out improvement works at the Orchard Estate, in Woodford Green, were burgled overnight on Wednesday.
The workmen locked their site office, in Navestock Crescent, at 7.30pm and when they returned at 6.45am yesterday morning, they discovered it had been ransacked.
Approximately £11,600 of equipment was taken, including drills, tools, a Samsung camera and three laptops.
Police would like to speak to five men - three black and two white - seen in the area between 11pm and 11.30pm on Wednesday evening to eliminate them from their enquiries.
Anyone with information is asked to contact Det Con Zoe Graham at Ilford Burglary Squad on 0208 345 2680 or Crimestoppers anonymously on 0800 555 111.
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