Police have recovered four suspected pipe bombs from a cemetery in Derry where a republican commemoration was staged on Easter Monday.
A senior PSNI officer has described the discovery as a “sinister and worrying development”.
Officers carrying out the security operation on Tuesday were attacked with petrol bombs, stones and bottles.
Derry’s City Cemetery was closed to visitors for much of the day after the discovery of a suspicious device at 6.30am.
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A PSNI spokesperson said: “Police have recovered four suspected pipe bombs from inside the City Cemetery in Creggan following a public safety operation there today, Tuesday April 11th.
“The operation was implemented following the discovery of a suspected pipe bomb in the cemetery just after 6.30am this morning. Following subsequent searches within the cemetery grounds, a further three suspected pipe bombs were discovered.
“These devices have been made safe and taken away for further forensic examination.
“All of these devices were located in the same area where clothes worn by participants in yesterday’s unnotified Easter parade were removed under the cover of umbrellas and burnt.
“For a time today, during the public safety operation, our officers again had petrol bombs, stones and bottles thrown at their vehicles.
“Two vehicles were damaged, but thankfully no officers were injured.”
The police operation has now concluded.
[ Petrol bombs thrown at police during dissident republican parade in DerryOpens in new window ]
PSNI Assistant Chief Constable Bobby Singleton said: “Last week we warned that we had strong community intelligence there may be attempts to draw police into serious public disorder in Derry/Londonderry, and to use that as a platform to launch terrorist attacks on police.
“That intelligence played out yesterday and today in the form of disorder, involving young children throwing ready-made petrol bombs and other missiles at police.
“The discovery of these devices was a further sinister and worrying development.
“The actions of those responsible are reprehensible and show a complete disregard and utter contempt for the community.
“These suspected pipe bombs were left in a cemetery, a place where people lay loved ones to rest and visit to pay their respects. That is absolutely shameful.
“Colleagues from Terrorism Investigation Unit will now lead on this investigation. Anyone who can assist their investigation is asked to call police, or contact Crimestoppers, which can be done anonymously.”
Mr Singleton added: “We understand today’s operation caused disruption in particular to those unable to access the City Cemetery.
“Public safety was our priority. We thank the public for their understanding, and our partners in the community for their support.”
Cordons were in place for much of the day and one home was evacuated.
Two robots, usually deployed to examine suspicious objects, were seen moving within the site.
One small funeral was held at the cemetery during the closure.
The operation was undertaken a day after the republican event at the cemetery.
Prior to the event at the republican plot in the cemetery, there were scenes of violence in the Creggan area of Derry when a number of missiles, including petrol bombs, were hurled by young people at a police Land Rover monitoring the pre-commemoration parade.
The illegal parade started in the Central Drive area when a number of masked men in paramilitary-style dress formed a colour party carrying the Irish flag and a host of republican flags.
As the parade progressed towards the City Cemetery, the police Land Rover came under attack, with masked youths throwing petrol bombs and firing fireworks before it drove off in flames.
Commenting on the security operation, Foyle MP Colum Eastwood tweeted: “People can’t get to the graves of their loved because of the actions of a few with no political mandate and no support.
“Hoping the city cemetery is made safe as soon as possible.”
Police Federation for Northern Ireland chairman Liam Kelly said those who left the pipe bombs are “callous individuals who would drag the Creggan and the city back to the dark ages of bitter and pointless conflict”.
He added: “I want to praise the steadfast and dedicated work of my colleagues.
“Furthermore, I would appeal to the many decent people in Creggan to tell the Police who the ringleaders are so that they can work to prevent them from inflicting devastating harm.”- Press Association