An internal MI5 investigation looking into possible intelligence failings over the Manchester bomber is the "right first step", the Home Secretary has told Sky News.

The Security Service has launched an urgent inquiry into how it missed the danger posed by attacker Salman Abedi.

The move comes amid claims he was repeatedly reported to authorities by teachers and religious leaders concerned that he might become a terrorist.

Investigators will be looking at the process used to assess suspects and asking if different decisions should have been made in Abedi's case.

:: Timeline: Salman Abedi's last-known movements


Image: The occupants of a property raided in Moss Side on Sunday posted a note on their door

While Abedi was a "former subject of interest" to the security services, he was not being actively investigated by counter-terror agencies at the time of the attack.

Despite concerns about whether an internal investigation is appropriate, Home Secretary Amber Rudd told Sky News: "I think it is right that they do this.

"In the future, we can look at anything else that might need to be done. As a first step it is absolutely right."

She added: "There's a lot of information coming out about what happened, how this occurred, what people might or might not have known.

Image: The man arrested in Shoreham is believed to have lived in a flat above shops

"I think it's right that MI5 takes a look to find out what the facts are. We shouldn't rush to make any conclusions at this stage."

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Mrs Rudd also confirmed that temporary exclusion orders, which stop potential terrorists returning to the UK after fighting in places such as Syria, have "just started to be used".

However, she refused to say how many times she had approved one of the orders.

"We don't offer that information out publicly," she told Sky News.

The Home Secretary said it was up to police and the intelligence services, with her approval, to decide when to request an exclusion order and insisted they have the "right tools".

Image: This CCTV image shows Abedi on the night he carried out the attack

Abedi, whose parents come from Libya, is thought to have received terrorist training in the North African country before returning to the UK just days before killing 22 people.

Fourteen men remain in custody on suspicion of being connected to the attack at Manchester Arena.

The latest - a 23-year-old - was arrested in the early hours of Monday in Shoreham-by-Sea, West Sussex.

The man was detained in a flat above a parade of shops in Brunswick Road in the town centre.

Two people told Sky News they believed a Libyan man lived there and that they had served him at their businesses.

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A landfill in Bury, Greater Manchester, was also being searched on Monday afternoon.

It followed earlier searches in Chester, and also in Whalley Range in Manchester. Neighbours there said the house was home to a Libyan family - a mother and her five children.

There were two further arrests in Manchester over the weekend - a 25-year-old in Old Trafford and a 19-year-old in Gorton.

But after a raid on a Moss Side property on Sunday - where three people were arrested then dearrested - the occupants posted a sign on their smashed-in front door.

It read: "This is what the police has caused and we have nothing to do with what happened in the bombing attack."

:: Bomb victim: 'It felt like fire in my back'

The NHS says 52 people are still being treated in eight hospitals after the attack, with 19 patients receiving critical care.

:: Victim's family: Government must 'open its eyes'

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The parents of one of the victims has urged the Government to "open its eyes" to the terror threat facing the UK.

Georgina Callander's family said the 18-year-old's life had been cut short by "evil, evil men prepared to ruin lives and destroy families".

The statement said: "I wish I could say that Georgina is one of the last to die in this way but unless our Government opens its eyes we know we are only another in a long line of parents on a list that continues to grow."