Dissident republicans are mounting a "serious and sustained escalation" of violence to mark the Easter Rising centenary, the police officers' representative body has warned.
The Police Federation for Northern Ireland expressed concern after a series of terror-linked incidents in recent days.
On Friday a prison officer was badly injured when a bomb exploded under his van in east Belfast.
On Saturday two viable explosive devices were found in west Belfast while on Sunday in Larne, Co Antrim, police recovered a terrorist weapons haul buried in a forest park.
Police commanders in the North have also warned that dissident extremists are intent on killing security force members as a perverse way of commemorating the landmark republican anniversary at the end of the month.
Federation chairman Mark Lindsay voiced similar concerns today.
"There are murderous republican gangs who think the best way to mark the centenary of the Easter Rising is to visit misery on the family of a police officer and society," he said.
"They are aggressively targeting officers, prison officers and soldiers in a worrying escalation. For them, success is measured in casualty numbers and anguish.
"Their cause is worthless and pointless. They are a throwback in time, relying on outdated rhetoric in their attempts to justify everything this entire community doesn't want.
"The irony is that most of them cannot remember the days of the troubles when the entire community was blighted by terrorism. They may belong to a bygone age, but they remain a dangerous band."
Mr Lindsay urged officers to take extra precautions.
"The threat level is at the highest it has been for quite some time and, for that reason, I am today issuing an urgent appeal to all police officers to heighten alert levels and double-check their personal security arrangements," he said.
"On or off duty, the men, women, mothers and fathers who tackle this threat head-on are the targets of these hideous murder gangs, and must exercise extra vigilance at this worrying time.
"We also call on individuals who would seek to support these terrorists to think how far we've moved on as a society, and where these groupings would have us return to in pursuit of their objectives."
