The person who made the bomb that blew up Manchester Arena is still at large and could strike again at any time.

Intelligence services now believe that Salman Abedi who detonated the nail bomb in the foyer of the venue was a ‘mule’ using a device made by someone else.

The bomb was a major step up from the crude but lethal attacks using vehicles at Westminster this year and in atrocities in Nice and Berlin in 2016.

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It was packed with nuts and bolts which would cause maximum injury in a confined space.

There are fears that whoever made the Manchester Arena bomb is on the run and could carry out one last attack.

A police source told the M.E.N.: "They don't waste bomb makers. The reason we have gone to critical is because he is still out there and the fear is that he will strike again before they get caught."

On Tuesday night Prime Minister Theresa May increased the UK terror threat level from severe to critical.

Earlier today armed forces carried out a raid at an address in Granby Row near Piccadilly Station. The operation was part of the investigation into the bombing.

Fire crews were on standby during the raid. It is not clear whether their presence indicated that the swoop was connected to the search for the bomb maker or bomb-making equipment.

ISIS have claimed responsibility for the attack.

(Image: PA)

As part of their inquiries police are trying to establish who Abedi met before he went to the Arena - and how he travelled there. Much of this is expected to have been caught on CCTV.

Abedi had returned to his home city of Manchester after vsiting Libya - the original home of his parents.

A senior French official has revealed Abedi is believed to have also recently travelled to Syria and had “proven” links with ISIS.

Interior minister Gerard Collomb said this morning that British and French intelligence have information the British-born attacker had been to the ISIS hotbed.

The MEN has set up a fundraising page to help support the families of the Manchester terror attack victims