The report, produced by Northern Ireland’s comptroller and auditor general Kieran Donnelly CB and the local government auditor Colette Kane, considers how the system has operated since April 2015, when responsibility for most planning functions moved from central government to local councils.

The Department for Infrastructure still retains a central role with responsibility for preparing planning policy and legislation, as well as monitoring and reporting on the performance of councils in delivering planning functions.

The report finds that there is significant silo working in the planning system, and that the most important planning applications are still taking too long to process.

Almost three-quarters of regionally significant and major planning applications processed between 2017-18 and 2019-20 were not completed within the statutory target of 30 weeks. Over half (56 per cent) had taken more than one year to process, and 19 per cent more than three years.

The time taken to process major applications varies substantially between councils, with the median processing time for the slowest council more than three times that of the fastest council.

The report highlights other notable variances between councils in their decision-making processes. These include the extent to which planning decisions are delegated from elected representatives to professional planning officials, and how councils resolve enforcement cases where there are potential breaches of policies or planning conditions.

It also warns that the planning system is increasingly financially unsustainable, with planning fees not having increased to match inflation in recent years against the backdrop of increasing complexity of planning decisions.

These financial pressures have also contributed to slow progress in the creation of Local Development Plans (LDPs) by councils, the report states.

LDPs are intended to provide a 15-year framework to direct and control the scale and type of development in each council area. However, seven years since the transfer of planning powers to local councils, none are complete and some LDPs remain at the early stages of development. The lack of LDPs means planning decisions are not guided by long-term, up-to-date plans.

Commenting on the report’s conclusions, Mr Donnelly and Mrs Kane said: “The planning system can be a key enabler for the economic and social development of Northern Ireland, as well as playing an important role in protecting the environment, and the focus of all those involved should be on ensuring it delivers its functions in an efficient, effective and financially sustainable way.

“The ‘planning system’ in Northern Ireland is not currently operating as one system. Rather, there is a series of organisations that are not interacting well and not delivering an effective service. Addressing the issues identified in this report will be both a cultural and a practical challenge, demanding strong leadership.”

Among its other findings, the report also highlights concerns over how the planning system is dealing with applications for developments that will produce ammonia emissions, which can contribute to serious, long-term harm to the environment and human health. A lack of clear environmental guidance in regards to levels of ammonia emissions has resulted in significant uncertainty for planning authorities and applicants, it says.