Three more arrested by police investigating Manchester bomb atrocity

They were detained after police executed warrants in south Manchester.

A total of four people have now been arrested as part of the inquiry into the atrocity.

Twenty-two people were killed and dozens more injured when suicide bomber Salman Abedi detonated a home-made device as fans left a concert by US star Ariana Grande at Manchester Arena on Monday night.

The latest arrests were announced by Greater Manchester Police as:

::France's interior minister disclosed that Abedi, 22, is believed to have travelled to Syria and claimed he had "proven" links with Islamic State;

::Home Secretary Amber Rudd confirmed UK security services had been aware of the British-born attacker;

::Military personnel were being deployed to key sites after the official threat assessment was raised to critical, the highest level, indicating that a further attack may be imminent;

::A Polish couple who had gone to the venue to collect their daughters were revealed to be among those killed;

::PR manager Martyn Hett was the latest person to be named as a victim of the atrocity.

Prime Minister Theresa May announced late on Tuesday that the terrorism threat level was being raised to "critical" - the highest alert level - meaning that an attack is thought be imminent.

It is the first time the most serious rating has been reached for nearly a decade.

The move reflects fears that a "wider group of individuals" may have been involved in the attack - including the bomb-maker who provided Abedi with his deadly device.

Following Monday's blast, the Government has activated Operation Temperer, providing up to 3,800 troops to support the police in their security operations.

Ms Rudd said the move was temporary but refused to be drawn on how long the heightened state of alert would remain in place.

"It is an ongoing operation which means that the investigation is continuing to find leads," she said.

"So until we can be reassured that there is no continued activity around this operation, that it is entirely safe around this operation, then it is right that we are at this heightened state of alert.

"It is operationally driven, it is intelligence-driven and we must make sure that we allow our counter-terrorist police, our police and our intelligence services to get on and do their job and this helps give them the space to do just that."

France's Interior Minister Gerard Collomb told French television that both British and French intelligence services had information that Abedi had been in Syria.

Mr Collomb said: "We only know what the British investigators have told us. He was a British national of Libyan origin, he grew up in Great Britain.

"All of a sudden he travelled to Libya and then most likely to Syria, became radicalised and decided to commit this attack."

When Mr Collomb was asked whether there was a terrorist network, he replied: "We don't know yet (if there's a network). In any case, links with Daesh (Islamic State) are proven."

Ms Rudd confirmed Abedi had recently returned from a visit to Libya, where his parents are reported to now live, and said the nature of the attack suggested he may have had support.

"It was more sophisticated than some of the horrific events that we have seen in the past or in other parts of Europe so people are reasonably wondering whether he did this on his own," she told BBC Breakfast.

She said the deployment of troops would enable police to step up security at various high-profile events over the coming days, including the Great Manchester Run.

Among the first victims to be named following Monday night's attack at a concert by US pop star Ariana Grande were eight-year-old Saffie Roussos from Leyland and teenagers Olivia Campbell, 15, from Bury and Georgina Callander from Chorley.

The Islamic State terror group claimed responsibility for the barbaric attack, which involved a home-made device packed with nuts and bolts which exploded in the venue's foyer as thousands of young people were leaving.

On Wednesday Greater Manchester Health and Social Care Partnership said 64 people are being treated with 20 in critical care in hospital. In total 119 people were taken by ambulance or made their own way to hospital following the blast.

A Libyan family, father, his wife and their two sons, aged in their late teens or early 20s, were taken away by armed police who raided a property on Aston Avenue, Fallowfield, at around 2.30am on Wednesday, neighbours said.

The house is less than a mile from the former home of Abedi.

Neighbour Omar Alfakhuri said at least six police vehicles arrived and armed police took the family out one by one, wearing their bedclothes.

Mr Alfakhuri said: "I was asleep, about 2.30 in the morning or twenty to three. I heard shouting so I thought there was hooligans in there at this time.

"But when I looked out of the windows I saw police cars, then I saw an armed police standing in the middle of the road with the police car on one side and a lot of police around.

"The first one I saw was the father of the family, he was in a t-shirt, very basic clothes, he was taken out from the house and he was shouting at him, the armed policeman.

"Then I saw the rest of the family were taken out, one after one.

"The last one I saw is the mum. The mum normally dresses in black and covers her hair but this is the first time I ever saw her in that type of clothing which looks like something being quickly pulled out of the bed or the wardrobe."

Mr Alfakhuri said the family had lived at the address for 15 years and described the father as religious who prayed at a local mosque.

A police cordon remains in place at Abedi's address in Elsmore Road, Fallowfield. Specialist Tactical Aid Unit officers arrived at the red-brick semi-detached house and entered the property.