Eight-year-old Saffie Roussos was one of the 22 people killed in the attack by suicide bomber Salman Abedi, 22, in May 2017.

Now her father, Andrew Roussos, has instructed solicitors to look into taking legal action against MI5.

Speaking on Sunday, he said a number of other victims' families have indicated they might join him.

He feels the security service should take "most of the blame" for the bombing.

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Manchester Arena: The security failings

This follows the results of an inquiry, released on Thursday 2 March, which found MI5 missed "significant opportunities" to prevent the attack.

Speaking on Times Radio, Mr Roussos said: "It's the only way to learn, everybody learns by hitting them hard in the pocket, I am sorry to say."

'Significant missed opportunity'

In the inquiry's report, chairman Sir John Saunders said that the security services (MI5 and counter-terror police) were guilty of a "significant missed opportunity to take action" that might have prevented the attack altogether.

It identified that the "principal missed opportunity" was two pieces of intelligence received by MI5 in the months prior to the attack, which were assessed to relate to "non-terrorist criminal activity" on the part of Abedi, who returned to the UK from Libya four days before the bombing.

This added to the other 20 times Abedi had been on MI5's radar, dating back to 2010.

Addressing this, Mr Roussos said: "In 2017 we were at the highest alert and everybody was warned of an attack in this country."

He said security was the "sole job" of MI5, adding that the security service is "well-funded and well-equipped" and had "22 pieces of information about Salman Abedi".

"So if they would have learnt lessons they wouldn't have allowed Abedi to walk into that arena," he said.

"So yes MI5 have, for me, most of the blame."

The public apology from the security service's director general, Ken McCallum, on 2 March, had come too late for Mr Roussos.

He said: "I can't accept apologies for losing Saffie, I want Saffie back in my life and I can't have that.

"If you want to make an apology something meaningful, apologise from day one, that would mean a lot more than waiting for an inquiry."

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Timeline: Bomber was on MI5's radar more than 20 times
The mistakes made by emergency services

Speaking to Sky News before the inquiry was released, Mr Roussos expressed similar anger with the security service.

He said that MI5 have "blood on their hands" having let Abedi "slip through the cracks".

A number of recommendations were made in the final of three reports from the inquiry, which spent months examining the events surrounding the terror attack.

Acknowledging the "difficult job" of MI5 and anti-terrorism police, Sir John said that if the security services make mistakes, they "need to be identified and steps taken to put them right".

The first report, released in June 2021, highlighted a string of "missed opportunities" at the arena venue to identify Abedi as a threat before he walked across the City Room foyer and detonated his device.

Sir John's second report, published last November, criticised the emergency services' response to the bombing.