Constable Ronan Kerr, 25, was killed when a bomb was triggered outside his home on the Highfield estate on Saturday afternoon.

The police have not identified those responsible for the attack but said there had been dissident threats in the area recently.

In a joint statement, the Archbishop of Armagh, the Most Rev Alan Harper, and the Bishop of Derry and Raphoe, the Rt Rev Ken Good, offered their “heartfelt prayers and sympathy” to the family of Constable Kerr.

The Church leaders said there were “no words to adequately describe the inhumanity” of the murder.

“The cruelty and shame of those who committed this act, either in planting the device or in supplying of information, is displayed to all of the world,” they said.

“It has brought needless devastation to the family of this young officer. It is also an act for which those responsible will indeed answer not only to their conscience but to their maker.”

The bomb which killed Constable Kerr was inside a plastic container that had been placed under his car. Police said they believed the bomb contained explosives weighing up to half a kilogramme and was most likely detonated with a tilt switch.

The Catholic Bishop of Derry, Dr Seamus Hegarty, said he was “shocked” by the murder.

“This gravely sinful killing is an offence against God, who created this young man in his own image and likeness, and it is a profound rejection of the fundamental Christian teaching that all human life is sacred,” he said.

“This crime, against a man who served and protected the public, is a crime against all in our society.”

Mr Kerr was a new recruit to the police, having joined in May last year.

Sinn Féin's deputy first minister of Northern Ireland, Martin McGuiness, urged anyone with information about the suspects to come forward to the police.

"I would say, and I am standing up to be counted, give the information to the police, give it to the Garda in the south if you have it, give it to the PSNI in the north," he said.

"My message is very, very simple: those who are perpetrating these acts, those who are killing our people, need to be apprehended.

"These are people who are pledged to destroy the peace and destroy a peace process that many of us have invested much of our adult lives in trying to bring about."

He added that dissident republican groups were waging a “useless war against peace”.