One of Britain’s most senior police officers has revealed that only four in every 10 crimes reported to his force is investigated.

Sir Peter Fahy, Chief Constable of Greater Manchester Police, said officers concentrated their efforts on serious crime or on incidents in which there were witnesses or a realistic prospect of achieving conviction.

He said most offences were committed by “active persistent offenders” who were targeted by police.

Download the new Independent Premium app Sharing the full story, not just the headlines

Sir Peter compared policing priorities to the National Health Service where managers concentrated resources on the most effective treatments.

“In practice, this translates into about 40 per cent of crime being actively pursued at any time. We look at all crimes to identify patterns of offending and to build the picture of where we need to target police patrols. In many crimes there are no witnesses, no CCTV and no forensic opportunities,” he said.

Local Labour MP Graham Stringer said the admission could damage public confidence in the police.

“I accept that they have to prioritise. I don’t accept that they should ignore the majority of crimes,” he said.

In the year to April the force received 177,000 reports of crime which meant 106,000 were not investigated, Mr Stringer added.

Tony Lloyd, Police and Crime Commissioner for Greater Manchester, backed his chief constable and said no effort was spared in bringing criminals to justice.

“What I don’t expect is where there are no witnesses or no evidential trail that the police go through a paper chase to simply tick boxes, but instead use intelligent policing to prevent a recurrence of those types of crime,” he said.

Greater Manchester Police is in the midst of making £134m cuts that will result in the loss of 2,700 jobs with the force.