Some parts of Northern Ireland's police force have been left "fatigued" by public order duties, with specialist units often deploying significantly under strength, senior officers have told inspectors.
The number of dedicated riot police has almost halved since 2000 as part of an overall reduction in the Police Service of Northern Ireland (PSNI) following the decision of the IRA and loyalists to lay down arms.
Signs of increased tension surrounding loyal order parades were evident throughout last year and the work load of public order police units has been on the rise, Criminal Justice Northern Ireland said.
The Inspectorate's report stated: "In the absence of an overall comprehensive strategic threat and risk assessment, it is impossible to say whether the reductions in TSGs (Tactical Support Groups or riot police) were entirely justified.
"It may well be that they were justified or indeed inevitable in the circumstances, given the significant pressures to reform and achieve efficiencies and normalisation. But the envisaged peaceful situation which was referred to by the Independent Commission on Policing in 1999 does not reflect the current policing environment."
A severe threat is still posed by dissident republicans opposed to the peace process and protests linked to restrictions on the flying of the Union flag from Belfast City Hall sparked violent stand-offs with demonstrators across Northern Ireland around the turn of the year.
The abolition of the full-time police reserve, financial pressures, reducing police numbers and the reducing public order threat helped spur the reduction in tactical support groups and a number of part-time public order units support the dedicated riot police. But an ageing workforce and injuries or restrictions on duty were underlying issues, the report said.
The independent review stated: "Various interviewees expressed the view that requests for public order support were often reduced to meet the available resource, rather than meeting the operational requirements. Senior officers also acknowledged the fact that some parts of the organisation were 'fatigued' by recent deployments and events."
With approximately 1,000 officers from a force of some 7,000 available for such deployments, increasing this number to create greater flexibility will result in increased training and other costs, the report warned.
"However, this would ultimately be more cost-effective than increasing the permanent capacity in TSGs, albeit inspectors felt a more fundamental review of the capability and capacity of TSGs was also required," the document said.