The Police Service of Northern Ireland the theft on July 6 was not reported until July 27 and then investigated.
Some 200 police officers and staff were not informed of the theft of devices and documents with data potentially affecting them for almost a month, the Police Service of Northern Ireland has confirmed.
The theft from a car parked in Newtownabbey emerged last week following news of a major data breach during which some details of 10,000 officers and staff were published online for a number of hours on Tuesday.
A police-issued laptop, radio and documents were stolen on July 6 from the car which is understood to belong to a superintendent.
The Police Service of Northern Ireland’s Information Security Unit was informed on July 27. Following investigations, the Information Commissioners’ Officer was informed on July 31, and officers and staff were informed on August 4.
On Saturday, Assistant Chief Constable Chris Todd said in a statement they believe the laptop and radio were deactivated “shortly afterwards”.
“We are confident no data has been lost from these devices and they are of no use to any third party,” he said.
“Our Information Security Unit were informed on July 27.
“As there was a delay, our Information Security Unit had to conduct their own enquiries to be clear on what accurate information could be conveyed to the Information Commissioners Office who were then informed on July 31.
“The precise nature of the missing data had to be confirmed before we could inform our officers and staff on August 4. We have worked with our Data Protection Officer and sought legal advice and guidance to ensure the information we provided to our employees was accurate.”
Last week, PSNI Chief Constable Simon Byrne said he is aware of claims that dissident republicans are in possession of information from the breach, but stressed that claim has not been verified.
Scores of officers have expressed concern for their safety in Northern Ireland, where police are under threat from terrorists – with the current level of threat assessed as severe, meaning an attack is highly likely.
A Threat Management Assessment Group has been set up by the PSNI for those concerned about risk. It had had 1,200 referrals by Friday evening.
Mr Byrne cut short a family holiday last week to return to Belfast to answer questions about the data blunder.
He was quizzed by political representatives at the Northern Ireland Policing Board on Thursday, and met with police officer and staff representative groups on Friday.
Mr Byrne said on Thursday he was “deeply sorry” about an “industrial scale breach of data”.