DISCLOSING sensitive evidence in public at the inquests into the deaths of the 22 people killed in the Manchester Arena atrocity would "assist terrorists" in carrying out similar attack, a coroner has ruled.

Sir John Saunders, who is presiding over the inquests, has granted applications by the Home Office and police to keep some evidence secret on the grounds of "protecting national security".

The inquests could now be converted into a public inquiry.

Last week's pre-inquest review hearing into the deaths in May 2017 was held in private to consider the applications over material related to the issue of whether the attack by suicide bomber Salman Abedi could have been prevented by the authorities.

In his ruling High Court judge Sir John said: "I have upheld the claims for PII (public interest immunity) by both the Secretary of State and CTP (Counter Terrorism Police North West).

"I have done that because I am satisfied, having heard the justifications for them, that to make public those matters would assist terrorists in carrying out the sort of atrocities committed in Manchester and would make it less likely that the Security Service and CT police would be able to prevent them.

"The balancing exercise strongly favours the material in question for not being disclosed. I will, of course, keep this ruling under review." He added that, as a consequence, his provisional view was that an "adequate investigation" could not be conducted within the frameworks of the inquests.

Lawyers for the families who have not seen the evidence the authorities want to withhold, stressed the need for as open an inquest process as possible.

John Cooper QC, representing a number of the families, told the coroner that the people making the application "are the very people who could potentially be severely criticised, and the ramifications of that are significant".

The inquests are set to examine the build-up and the attack itself, security at the arena, the emergency response and the victims and their cause of death.

They will also look at whether the attack could have been prevented and the role of the police and security services.

Sir John said that the risk identified by both parties was that disclosure of the information "will make it easier for terrorists to kill people by avoiding detection before they are able to carry (out) an attack". The excluded evidence would likely be held in private at a public inquiry without the families of the victims and their lawyers.

Potential opportunities to stop the Manchester bombing were missed as a result of a catalogue of failings by security services, a report concluded last November.

A number of shortcomings in the handling of Salman Abedi before he launched his suicide attack were detailed by Parliament's Intelligence and Security Committee (ISC).

Abedi, 22, first came to the attention of MI5 in December 2010 and was briefly investigated by the agency in 2014.

The ISC assessment said:

- Abedi visited an extremist contact in prison on more than one occasion but no follow-up action was taken by either MI5 or police

- MI5 decided not to place travel monitoring or restrictions on Abedi, meaning he was allowed to return undetected to the UK in the days before he carried out the attack

- MI5 systems moved too slowly after Abedi's case had been flagged for review

- Abedi was not at any point considered for a referral to the Prevent anti-terror scheme

A Home Office spokesman said: "It is vital that those who survived or lost loved ones in the Manchester Arena attack get the answers they need, and that we learn the lessons whatever they may be.

"That is why it is right that an inquest is being conducted, and any decision to claim Public Interest Immunity is only taken when there is a risk of undermining our national security. The coroner's ruling today recognises that that risk applies in this case.

"If the coroner decides that an inquest cannot satisfactorily investigate the deaths the Home Secretary will carefully consider any recommendations they make."