Loved ones of the 22 murdered in the Manchester Arena terror attack have "grave misgivings" about the "obsessive secrecy" of MI5 and the security services, the public inquiry into the bombing heard.
Peter Wetherby QC, representing seven of the families of victims, said a central issue of what the security services knew about the bomber Salman Abedi and what they did, will be held in "closed hearings" without the families' lawyers, press or public allowed to attend.
Some evidence, involving information judged to be potentially of use to terrorists, is subject to restriction orders and those hearings will be closed, as the evidence is deemed critical to national security.
But Mr Wetherby highlighted that much of what is known about the bomber and his background came via the media and not through official channels or the authorities.
He said the relationship between Salman Abedi and known terrorist Abdalraouf Abdallah was an example of the "alarm" of the families at the prospect of closed hearings.
Abdallah, also from Manchester and jailed for terrorist offences in the UK, was twice visited in jail by Salman Abedi and the two discussed martyrdom attacks.
They were in contact before, during and after his Abdallah's conviction and in the months leading up to the Arena attack.
Yet in official reports and in an MI5 statement from a witness X submitted to the inquiry, the security services had redacted Abdallah's name and he is only referred to by a letter.
Mr Wetherby said:
He continued: "The failure to recognise the association between Salman Abedi and Abdalraouf Abdallah was a real missed opportunity.
"The redaction and omission of Abdallah's name from reports and the witness statement is an indication of a lack of transparency by the security services and frankly it calls for a rethink by this inquiry.
"Without the media exposure would there have been an attempt to keep Abdallah's name out of this process?"
He again cited press reports detailing the Abedi's links to extremism, his "radicalised" family and association with terrorists.
Mr Wetherby added: "What exactly does one have to do to get the attention of the security services?"
Mr Wetherby said a public inquiry must "pull no punches" and be a "warts and all" investigation and the families accepted the need to keep some information of use to terrorists private.
However, they also recognise that a veil of secrecy is likely to do the opposite.
Overbearing secrecy does not protect national security, it does the opposite.
It protects failure and it prevents progress. It undermines confidence.
Justice requires that light is shone into the darkest corners.
He said confidence in the inquiry from families is "high" but if MI5 is seen to be treated differently during the inquiry then "confidence will inevitably wane" and findings based on hearings held behind closed doors "will be met with scepticism".
The inquiry was adjourned until Tuesday morning