PSNI Assistant Chief Constable Bobby Singleton has said police have received strong community intelligence that dissident republicans are planning to launch terror attacks against officers on Easter Monday.
It is the day dissident republicans traditionally mark the anniversary of the Easter Rising rebellion against British rule in 1916, with a parade set to take place in Derry.
"It's going to be a really significant weekend for the PSNI," Mr Singleton told a press conference in Belfast.
"And there is also very strong community intelligence specifically coming forward in respect of Monday's events in Derry/Londonderry and a real concern that there may be attempts to draw police in to serious public disorder and to use that then as a platform to launch terrorist attacks on police as well.
"So going into our operation that's something that is very clearly right at the forefront of my mind, the minds of the commanders that will be delivering that and of course our officers as well."
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PSNI assistant chief constable Chris Todd said there was no specific intelligence that the anniversary of the Good Friday Agreement was acting as an additional motivation for dissident republicans to launch attacks.
"We plan for the worst and we hope for the best to be quite frank, we will respond to the intelligence as it develops, we have no such intelligence that would support that at the moment," he said.
Mr Singleton said while dissident republican intent to kill police officers remained the same he said officers were concerned they may use public disorder in Derry as a platform to launch attacks.
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"The intent remains the same. I think as I see it, it's the risk, it's the platform potentially, in particular, that public disorder may present," he said.
"We don't have to go too far back sadly, to see precisely that kind of scenario playing out in Derry/Londonderry in the past.
"So that is absolutely something that's in the mind of myself and the police commanders as we approach that event, and it will be something that we'll have to keep under constant review depending on how things develop on the day."
On the prospect of guns or explosives being used to target police in Derry, Mr Singleton added: "We've seen that in the past and, on that basis, we have to be prepared for that and we will be prepared for all eventualities on Monday."
Mr Singleton was asking whether police would adapt their response to any public disorder situation, given the intelligence over a potential terror attack.
"We tend to have the same standardised decision-making framework that we apply to events," the PSNI officer said.
"But, of course, what's different is the events themselves, their nature.
"So it really involves a dynamic assessment of all the various factors. But, yes, in the background, given where the terrorist threat is at the minute, it's going to be a very real and live concern for us, in terms of how we go about addressing any issues that arise on the day."
Mr Singleton was asked whether he believed dissident republicans had moved weapons into Londonderry ahead of Monday.
"The attack on our colleague John Caldwell (in Omagh in February) has demonstrated the capability and access some of these groups have to firearms in particular," he said.
"You know, the threat level almost speaks for itself in terms of an attack being highly likely.
"Again, the shift in our posture is a reflection of our understanding of capability and intent."