THE Home Secretary has admitted she does not know how many jihadis have returned to the UK from Syria and warned the terror network behind the Manchester bomber could still be at large.

Amber Rudd said the hunt for Salman Abedi’s accomplices continued at “full tilt” – but added members of the suicide attacker’s circle were “potentially” unaccounted for.

A picture emerged over the weekend showing Abedi minutes before he attacked concert goers at the Manchester Arena. The bomber, who had a Libyan background, is believed to have visited Syria.

The UK Government last year said it thought some 800 Britons had gone to Syria, to Islamic State (IS), and half had come back.

But yesterday, Ms Rudd admitted the UK Government does not know how many have returned.She said: “We don’t know the exact number. What we do know that is, in engaging with the intelligence services, and with the police, and with the border force, we made sure that they have to the tools to track them and keep them out where we can.”

She also confirmed the Government has started using temporary exclusion orders – which prevent British terror suspects returning to the UK – but would not reveal how many orders had been issued.

Ms Rudd said the UK intelligence services had foiled 18 terror plots since 2013, but insisted more must be done to keep people safe.

“I believe there is information that we can gather and there are steps we can take to improve this country’s security,” she said.

“We’ve invested in our intelligence services, we’ve invested in counter-terrorism… there will be as many armed police by the end of this year as there has ever been.”

The Manchester suicide bombing left 22 dead, including seven children, and scores injured. It is the worst atrocity to hit Britain since the July 7 attacks in 2005.

The huge police operation that followed saw raids in several cities as counter-terror efforts were focused on cornering his suspected criminal ring.

Ms Rudd said: “It’s an ongoing operation, there are 11 people in custody, the operation is still at full tilt, in a way. Until the operation is complete, we can’t be entirely sure that it is closed.”

She said IS, also known as Daesh, was trying to “weaponise” young Britons and defended the work of the security services after claims warnings about Abedi were not followed up.

The murderer had been a former “subject of interest” to MI5, but Ms Rudd said: “The intelligence services are still collecting information about him and about the people around him. But I would not rush to conclusions... that they have somehow missed something.”

She added: “What this reminds us is the scale of the problem that we have, the enemy that we have, Daesh, that is trying to weaponise the young people in our society.”