A shale gas firm has been accused of "getting away with whatever they want to do" by anti-fracking protesters after breaching planning rules.
Last month Cuadrilla took delivery of a drilling rig at its Little Plumpton site outside permitted working hours.
Lancashire County Council denied letting the firm off but did not demand the removal of the rig.
Campaigners have accused Cuadrilla of "riding roughshod" over planning enforcement policy.
About 30 wagons took a disassembled drilling rig into the site 04:45 BST on 27 July.
But under a Traffic Management Plan, delivery or removal of materials is only permitted between 07:30 to 18:30 on weekdays.
Cuadrilla said the delivery was organised in consultation with the police and "avoided congestion" caused by daily protests.
A spokesman added: "We understand Lancashire County Council need to investigate and are fully cooperating with that investigation."
Bob Dennett from Frack Free Lancashire said: "They are riding roughshod.
"If you try building a garage without the proper planning permission, or breach the planning conditions, they'd be down on you like a tonne of rocks.
"Either the convoy should have been stopped in the first place or Cuadrilla should remove that equipment from the site and comply with the traffic management plan and the planning conditions that restrict their working hours."
Council leader Geoff Driver said the delivery "didn't inconvenience any local residents".
He added: "If there's a serious breach of the conditions the county council would take serious action, but it's always got to be proportionate as to what the breach of conditions is.
"It wouldn't be appropriate to go into the details, but Cuadrilla haven't just been let off."
The rig will be used to drill two horizontal wells at the Preston New Road site.
A pilot well, approximately 3,500m (11,500 ft) deep, will be drilled first to identify the best place for horizontal wells.