PSNI Chief Constable Sir Hugh Orde today said Police Ombudsman Nuala O'Loan's report into security force collusion made shocking reading.
The report details findings of an investigation into security force collusion with loyalist paramilitaries in Belfast during the 1990s.
"The report makes shocking, disturbing and uncomfortable reading," he said. "It doesn't reflect well on the individuals involved, particularly those responsible for their management and oversight."
But Sir Hugh insisted that systems were now in place ensuring the situation described by the Ombudsman would never happen again.
"While I appreciate that it cannot redress some of the tragic consequences visited upon the families of those touched by the incidents investigated in this report, I offer a wholehearted apology for anything done or left undone."
Sir Hugh said he accepted all the recommendations.
"Significant reorganisation and the new systems and processes to deal with this most difficult area of policing which we have put in place over the last four-and-a-half years will ensure that the situation described by the Ombudsman could never happen again in Northern Ireland."
He expressed concern about the Ombudsman's finding that co-operation with her office from police had not been adequate and pledged to tackle the matter.
