A chief constable has been castigated after accusing Hillsborough families of lying in their accounts of the disaster.
The police watchdog said South Yorkshire chief David Crompton's comments had been "at best ill-judged and at worst offensive and upsetting".
They were contained in an email to senior police colleagues, sent last year, which has been published under the Freedom on Information Act.
Crompton, who has apologised for the slur, wrote: "One thing is certain - the Hillsborough Campaign for Justice will be doing their version ... in fact their version of certain events has become 'the truth' even though it isn't!!
"I just have the feeling that the media 'machine' favours the families and not us, so we need to be a bit more innovative in our response to have a fighting chance otherwise we will just be roadkill."
It was sent as part of South Yorkshire Police's preparations for the publication of the Hillsborough Independent Panel report last year.
It discussed how the force could use its website to respond to the findings of the panel.
When the report was published, it provoked widespread condemnation of the force's response to the disaster at Sheffield Wednesday's ground in April 1989, which left 96 Liverpool fans dead.
It revealed how dozens of police statements had been altered to portray police in a better light.
South Yorkshire Police's response to the tragedy is currently subject to a huge inquiry by the Independent Police Complaints
Last month, the Police and Crime Commissioner of South Yorkshire, Shaun Wright, wrote to the IPCC when he was made aware of the emails and associated documents.
Today, IPCC Commissioner Nicholas Long said the majority of the emails and documents he considered "raises no issues".
But he said one email from the chief constable "caused me concern".
He said: "It referred to preparing what 'amounts to the case for the defence' and stated that the 'Hillsborough Campaign for Justice's ... version of certain events had become the truth even though it isn't'.
"I consider that this is at best ill-judged, and at worst offensive and upsetting.
"I have written to Chief Constable Crompton to express these views.
"Families and individuals affected by the Hillsborough tragedy, along with the wider public, will rightly be concerned over the apparent attitude displayed by this communication within the highest ranks of the force which is currently under investigation in relation to the actions of its officers and staff around the disaster."