The Preston New Road Action Group, which is against shale gas drilling in Little Plumpton, says 13 placards showing opposition to fracking have been deliberately stolen.
Applications to frack at two sites on the Fylde coast, off Preston New Road and in Roseacre, near Elswick, by Cuadrilla Resources, are currently being considered by Lancashire County Council.
Bright yellow signs have appeared along roads and outside homes in the Weeton area, bearing the logo of campaigners Frack Free Lancashire and erected by those opposed to the controversial method.
It is these that campaigners now say have been deliberately taken.
Police have confirmed they are investigating the alleged theft of 13 signs, worth around £10 each, from public routes in Weeton village.
A spokesman for the neighbourhood policing team in Weeton said: “We are investigating a report of signs being stolen from Weeton.
“The incident happened at around 1.45am on March 14.
“It is believed that 13 may have been stolen, worth around £10 each.
“It was initially reported that one had been taken but it has since transpired others have been removed.”
Patricia Davies, chairman of the Preston New Road Action Group, said those with strong opinions on the matter should not be deterred from voicing them.
She added: “We believe there is a group operating in our area apparently determined to intimidate us and stop us from voicing our objections to fracking.
“The people doing this show absolute contempt for residents’ opinion, or indeed their right to express an opinion on their own land.
“Theft is not a minor offence when it is committed on a large scale like this, and at dead-of-night.
“We hope the police will now conduct a full investigation and carry out their job, to protect our community.”
Fracking is the process of injecting water and chemicals are pumped underground at speed to crack, or fracture, shale rock in order to release natural gases.