The police have apologised to 115 people – including dissident Republicans – after they were stopped and searched without correct approval.
A “technical error” meant the individuals were subjected to unlawful police action.
The fault lay within the paperwork which had been signed-off by an individual who was not properly authorised to do so.
The incidents happened between 30 July and 11 August.
In Northern Ireland, the police have the power to conduct stop-and-search under different laws – in this case it was the Justice and Security (Northern Ireland) Act (2007).
Under it, officers can search individuals as part of counter-terrorism work or if there is a risk of serious violence or disorder, without the need to have reasonable suspicion.
But approval must be signed-off for periods of up to two weeks at a time.
In a statement admitting fault, the Police Service of Northern Ireland said the mistake was administrative and involved an officer who had not been promoted to a rank high enough to authorise the action.
“An error occurred because it was considered and signed by an individual who was an acting assistant chief constable, rather than being temporarily promoted to the role.
“We have written to those individuals involved to inform them the stop-and-searches were invalid and to apologise for any inconvenience caused.”
Lessons have been learned, it added.
Some of the individuals were subjected to more than one stop-and-search, but it is understood none of the incidents resulted in a person being arrested or charged with any offence.
It is understood loyalists were also among those involved and three of the 115 people were aged under 18.
The PSNI said it has notified the Police Ombudsman and the Independent Reviewer of Justice and Security as part of “transparency around the powers”.
Its statement concluded: “As a police service, we use stop and search only when necessary for the protection of our community.
“We welcome the strict scrutiny and accountability that is in place to ensure the powers are used properly.”