Mr Durkan was speaking following a board meeting on Tuesday, after which it was announced there would be an independent review into the breaches.
The independent review will publish an initial report within a month and a full report by the end of November.
It will be led by Peter O’Doherty who is an assistant commissioner at City of London Police.
Said the Foyle MLA: “The independent review announced by the board on Tuesday marks the start of a long process to establish just how these data breaches was allowed to happen and how rank and file PSNI officers and support staff were put in such serious jeopardy to the point where we are told their details have now fallen into the hands of dissident republicans.
“There is still a long way to go before the PSNI leadership can restore confidence both internally and externally.
“We have heard from many officers about how badly they have been impacted by these data breaches and it has further undermined hard-won public confidence in policing here.
“Measures needed to restore it include ensuring this review is robust, follows a strict timeframe and the resources are made available to implement its recommendations as a matter of urgency.
“I’m disappointed that my call for part of Tuesday’s meeting to be held in public wasn’t acted upon.
“On Tuesday the public could have seen the political parties and independent members of the board hold the police publicly to account in the eye of a crisis. This did not happen.
“I also cannot understand why police did not appear before the media after the meeting at a time when confidence is low around policing, particularly when despite being challenging the general tone of the meeting was constructive.
“If the PSNI is to reassure its officers, staff and the public that they are taking the necessary steps to address the events of the past few weeks then we need to see strong leadership from the front and Tuesday was an opportunity to do so.
“I would hope to see further public communication from the PSNI in the coming days.”