Police are conducting searches at an anti-fracking protest camp after a flare was allegedly fired at a police helicopter.
A flare was aimed directly at the approach path of the aircraft as it came into land at Barton airfield in Eccles, Greater Manchester, police said.
The aircrew said it appeared to come from the nearby campsite in Barton Moss Road at about 12.15am on Saturday.
But protesters countered that no flare had been fired from the camp and claimed Greater Manchester Police were using the incident as an excuse to search through their property.
Since November, campaigners have been positioned at the drilling site in Barton Moss, between Barton Aerodrome and the M62.
Energy company IGas was granted permission for exploratory gas drilling and says it is seeking methane and shale gas but has no plans for fracking.
Police chiefs labelled Saturday's incident as an "unbelievably stupid act of criminality" which could have caused a "catastrophic situation".
Chief Superintendent Mark Roberts, of Greater Manchester Police (GMP), said: "This was an unbelievably stupid act of criminality which was extremely dangerous, not only for the police helicopter, but all other aircraft that use the nearby Barton airfields and the wider public.
"Had this flare caused an emergency situation it would not only have been catastrophic for the aircraft and its crew but potentially for numerous homes near the airfield, the M62 motorway and a children's residential facility.
"The protest camp appears to be a tight-knit group who seem to be continually filming anything occurring on Barton Moss Road.
"If one of the protesters is responsible, I suspect their identity will be known to others and I would expect those reasonable members of the anti-fracking campaign to provide any information they have to the police.
"An attack on the police of this nature has nothing whatsoever to do with whether or not exploratory drilling is right or wrong. Whilst I recognise the genuine concerns of many of the protesters in relation to exploratory drilling, it is obvious that there is also an element of regular protesters from outside the Greater Manchester area who seem more interested in seeking confrontation with the police.
"GMP continue to balance facilitating peaceful protest with the rights of others to go about their lawful business, whilst minimising disruption to the local community and businesses.
"Because of the way the camp is set up we have to systematically search the site under a warrant issued by a local court.
"We will attempt to facilitate this through dialogue with protesters but we have to take all reasonable steps to ensure there is no repeat of this action near to the airfield and that we identify those responsible.
"We have therefore had no option but to carry out this action.
"We are very grateful to the residents of nearby communities, who are well aware of the need for safety at the airfield, for their ongoing patience with regards to this matter."
Sacha Conway, a resident at the Barton Moss Community Protection camp, said: "No flare was fired from this camp on Saturday or any other day. We would condemn any such action as aggressive, violent and in breach of our very strict safe spaces policy. We are peaceful people who wish to stop the destruction of this land by IGas and all of the other fracking companies.
"The only violence that we have seen has been conducted by Greater Manchester Police. This is just an excuse to search our through our property and gather evidence."
Rachel Thompson, from Frack Free Greater Manchester, added: "We refute this claim. Greater Manchester Police have refused to show any evidence of this alleged incident. The behaviour of Greater Manchester Police has been outrageous throughout this whole campaign. In our eyes this is just another aggressive tactic aimed at isolating the camp from the community and to put them in a bad light.
"'We have asked for a meeting with the Police Commissioner, Tony Lloyd, to discuss the disgusting behaviour of his officers and have been refused. This matter is now with our lawyers but we wish to make it clear that we stand by Barton Moss Community Protection Camp and we call for an inquiry into this alleged incident."
Police have been called to the drilling site on a number of occasions and made arrests as protesters have made various attempts to stop lorries entering by erecting blockades such as a giant wind turbine blade and a bus.