The Environment Agency has warned fracking firm Cuadrilla over three more breaches of its permit at the Preston New Road drill site.
The EA wrote to the shale gas firm over failing to monitor groundwater properly for key substances and then failing to tell the EA about the missing data.
Anti-fracking protesters said it was no surprise following earlier breaches which included allowing unburned methane gas into the atmosphere, spillages into a nearby brook , to failing to store waste water properly.
A Frack Free Lancashire spokesman said: “This is the third time that Cuadrilla have received a written warning for a range of environmental breaches.
"It is time for Cuadrilla to back their bags and leave town
"They have shown themselves to have a totally cavalier attitude to the regulatory regime and it is clear the safety of the community is a low priority for them.”
But Nick Mace, from Cuadrilla, said just a small number of data points were missed out. He said: “Cuadrilla takes its environmental responsibility extremely seriously.
"Since January 2017 we have had around 40 inspections and audits from the Environment Agency, with no material breaches of our permits.
We are therefore disappointed by this letter and I would like to reassure people that there is no suggestion whatsoever of any environmental harm.
"We are confident that the minor data gap has now been addressed. Preston New Road is one of the most monitored oil and gas sites in the world and Cuadrilla has proven that this site is a safe and well run operation.”