A report into the Manchester Arena attack recommends public bodies dealing with families of the bereaved adopt rules inspired by the aftermath of the Hillsborough disaster.
An independent panel, appointed by the Mayor of Greater Manchester Andy Burnham, has been looking at the preparedness and response to the terror attack from local public bodies.
Suicide bomber Salman Abedi left 22 dead and hundreds injured when he detonated his device at the end of an Ariana Grande concert on May 22 last year.
Lord Bob Kerslake, supported by a panel of experts, was asked to assess Greater Manchester's preparedness, explore the response of the different agencies and emergency services, identify good practice, and look at any opportunities to strengthen the response to future terror attacks.
His interim report released on Friday recommends public bodies in Greater Manchester adopt a "Charter for families bereaved through public tragedy" that was inspired by the Hillsborough families and proposed by The Right Reverend James Jones KBE in his report published in November last year, entitled "The patronising disposition of unaccountable power".
The charter asks organisations to commit to learning lessons from Hillsborough to ensure the perspective of bereaved families is not lost in any future public tragedies.
It commits public bodies to "becoming an organisation which strives to" support the bereaved and vulnerable, put the public interest above their own reputation, assist the search for truth by being open and honest under scrutiny, be held to account and not mislead the public or the media.
The panel spoke to the bereaved and injured, emergency services, NHS, local councils and around 170 people, including young people at the concert on the night of the attack.
Lord Kerslake said: "The panel wants to ensure that the ethos of putting families first isn't lost following this tragedy or in the future, that's why we are recommending Greater Manchester adopts the 'Charter for families bereaved through public tragedy' that was introduced as part of the Right Reverend Jones' report.
"Throughout the review we have given everyone the chance to have their say and share their experiences of that dreadful night and the days that followed - good or bad - so we can look at what worked well and learn any lessons for the future."
Mr Burnham said: "When I commissioned this review I wanted first and foremost to make sure that the families of those killed and the seriously injured were at the heart of the process and as the progress report outlines, the panel have worked hard to give everyone the opportunity to have their voices heard in the most appropriate way - whether that be via face-to-face meetings or by sending their written accounts.
"I have had the opportunity myself to meet many of the families who lost loved ones and many of the injured and what they have said is that they want the final report to be honest in telling the story of what happened that night.
"I have worked with families bereaved through public tragedy before and often what compounds their distress is a failure to get to the truth and I am determined that doesn't happen here.
"That is why I am calling on all public bodies in Greater Manchester to provide their fullest cooperation to Lord Kerslake and the panel as it completes its review, and I would encourage every public body in the city region to sign up to the charter as proposed by the panel today."
The full report is expected to be published in March.
Anyone affected by the Manchester Arena attack can visit a dedicated website for advice, information and support www.manchesterattacksupport.org.uk