By Ian Dunt
The political fallout over the murder of a police recruit in Omagh is continuing, with David Cameron warning of a return to "a dark and bloody past".
Twenty-five year old Catholic police recruit Ronan Kerr was killed when a bomb strapped to his car detonated outside his home in Omagh, County Tyrone at around 16:00 BST yesterday.
Dissident Republican groups are suspected of the attack although none have claimed responsibility.
Sinn Fein President Gerry Adams rejected those responsible for the murder.
"It is imperative that everyone make clear their opposition to the murder of Constable Kerr," he said at a press conference.
"Every citizen must defend the process. This action and those responsible for it must be totally rejected. I am calling upon those involved to stop and to stop now."
Mr Cameron said: "Those who carried out this wicked and cowardly crime will never succeed in dragging Northern Ireland back to a dark and bloody past.
"Their actions are rejected by the overwhelming majority of people right from all parts of the community."
Labour leader Ed Miliband said the attack was an "appalling outrage".
"My thoughts are with the victim and his family," he said.
"I know that people and politicians will not let this atrocity divert them from the path of peace they have chosen."
The murder prompted fears across the political spectrum that there could be a return to violence as terrorist groups try to destabilise Northern Ireland.
The location of the attack in Omagh, which was the site what many consider the country's worst ever terrorist atrocity in 1998 when 29 people were killed in a Real IRA bombing, brought back dark memories of the region's political history.
Matt Baggott, chief constable of the Police Service of Northern Ireland said it was one of the "saddest evenings" of his career.
"Tonight is one of the most sombre and saddest evenings of my service, tonight tragedy has returned to Omagh," he said.
"I have no words to describe the awfulness of the events of this afternoon and my abhorrence and anger at this wasted life."
US secretary of state Hillary Clinton said: "The perpetrators of this cowardly act represent the failures of the past, and their actions run counter to the achievements, aspirations and collective will of the people of Northern Ireland."