Oversight of An Garda Síochána is “not possible” because the force is continuing to conduct criminal and disciplinary investigations into its own members without informing the Garda Síochána Ombudsman Commission (Gsoc), the commission has said.

Gsoc, which investigates complaints made about gardaí, said it was only becoming aware via media reports of some serious incidents involving Garda members that were being investigated internally.

It also said it did not know how many gardaí were investigated internally each year because that information was not available.

And it warned the Government that a new oversight body, planned for the Garda, would lose credibility unless it was staffed properly and the practice of gardaí investigating gardaí was ended.

“The concern would be that without proper planning, delay and a resulting erosion in public trust in a new body will set in at an early stage,” it said.

The commission also notes that 22 protected disclosures were made to it in 2017 for investigation, twice as many as were made to the Garda.

This was due to “confidence in Gsoc to treat these disclosures respectfully or a lack of confidence in the Garda Síochána to investigate disclosures independently”.

Áras intruder Serious incidents that Gsoc first became aware of via the media included a case involving an intruder gaining access to Áras an Uachtaráin. The intruder drove on to the property, gained access to the main house and walked into President Michael D Higgins’s office and spoke to him before driving away.

In another case a submachine gun fell out of a Garda car and was unaccounted for until handed into a Dublin Garda station by a member of the public. On another recent occasion a Garda member was arrested for questioning about a criminal matter.

The incidents referenced by Gsoc before and after last September, when the Garda Commissioner Drew Harris was appointed and Commission on the Future of Policing in Ireland published its findings.

Gsoc said the commission had expressly concluded that all inquiries into gardaí and Garda matters should be routed through Gsoc.

It added that the Garda not informing it of investigations “runs the risk of allegations of cover-up or bias or corruption when it becomes known”.

In other cases, Gsoc said it knew nothing of investigations under way within the Garda until the cases reached the courts. And it did not know how many other internal investigations were conducted that never emerged publicly.