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Derby City council say next Saturday's switch on will go ahead as planned.
£20,000 worth of lights, tools, cables and equipment were stolen from storage at Markeaton Park early on Thursday morning.
A Cherry-picker lorry was also taken - but later found abandoned.
There was another attempted break-in on Saturday but nothing was taken.
Phil Derbyshire, Head of Energy and Maintenance, said:
"Security to the building has been further increased with assistance from the University of Derby and the Police. New lights for the tree are on order and we are currently back on track for the Christmas Lights Switch-On on Saturday"