The level of terrorist activity in Northern Ireland is being played down by the police and government to make NI appear more normal than it actually is, the Police Federation has claimed.
When asked about the number of terrorist incidents this year, police say there have been 39 attacks on "national security targets"
But its website lists the total number of shootings and bombings as 150.
The discrepancy has been a deliberate policy, the Police Federation claims.
The PSNI dismissed the allegation as "nonsense".
Terrorist incidents are classified according to the target, not who carried out the attack.
If the target is a police officer or soldier, or a government building like a court house, it is termed a national security incident.
However, attacks on civilians or commercial targets are not.
So the bombing of Newry Courthouse is officially termed a national security incident as is the attempted murder of police officer Paedar Heffron.
But the murder of Keiran Doherty by the Real IRA, and dozens of other shootings and bomb attacks by dissident republicans and loyalists, are not.
The Police Federation, which represents rank and file officers, believes the classification is part of a conspiracy to give a false impression of the level of terrorist activity.
Senior police officers refer to national security incidents when asked about the level of terrorist activity.
However, the PSNI's website provides a much broader picture.
It lists figures for all shootings and bombings for each year since 1969.
So far this year, it records 72 shootings and 78 bombings, giving a total of 150.
Terry Spence of the Police Federation said that was not good enough, and that more transparency was needed.
"It's very clear that the PSNI, the Department of Justice, the Home Office and the Northern Ireland Office are using the statistics that there have been 39 national security targets attacked in Northern Ireland since the beginning of the year," he said.
"From our own statistical information that we have gathered over the last 11 or 12 months, in fact there have been 150 attacks, not only on police targets, police establishments and officers both on and off duty, but also on the family members of police officers and on civilians - two of whom have been murdered.
"It's very clear that all of those agencies, all of those stakeholders, have been understating the level of the terrorist threat both from dissident republicans and indeed from loyalist paramilitaries."
The Police Federation said it had raised the issue with Chief Constable Matt Baggott and was confident that senior officers will in future refer to the overall number of shooting and bombing incidents when asked to quantify the level of terrorist activity.
In a statement, the PSNI said it refutes any allegation that it is trying to understate the current terrorist threat.
It added that the chief constable is on record on a number of occasions stating the severe level of threat, and pointed out that tens of millions of pounds has spent countering that threat during the past 12 months.