Salman Abedi perpetrated the worst outrage Britain has seen in a decade just days after returning from Libya, according to reports.

The 22-year-old's visit to his family's native country fuelled concerns he was preparing for Monday's deadly assault under the guidance of hardened jihadists.

The Times reported the Manchester-born bomber spent three weeks in the war-torn north African nation before the attack on Manchester Arena, in which he was killed.

A friend told the paper: "He went to Libya three weeks ago and came back recently, like days ago."

Both Islamic State (IS), who claimed responsibility for the atrocity, and al Qaida have a presence in Libya, but the possibility remains that Abedi travelled to their heartland in Syria for training.

Prime Minister Theresa May said on Tuesday night it was possible he had planned his deadly attack with a "wider group of individuals".

Born and raised in Manchester, Abedi grew up in a Muslim household - but matured into a university dropout with an appetite for bloodshed.

He was registered as living at Elsmore Road as recently as last year, where police raided a downstairs red-bricked semi-detached property on Tuesday.

Neighbours recalled an abrasive, tall, skinny young man who was little known in the neighbourhood, and often seen in traditional Islamic clothing.

He is thought to have lived at a number of addresses in the area, including one in Wilbraham Road, where plainclothes police made an arrest on Tuesday.

Abedi previously lived with his mother Samia Tabbal, father Ramadan Abedi and a brother, Ismail Abedi, who was born in Westminster in 1993.

He is thought to have a younger brother, Hashim Abedi, and a sister Jomana, whose Facebook profile suggests she is from Tripoli and lives in Manchester.

A family friend, who asked not to be named, said they were known to the Libyan community in the city and described Abedi as "normal".

He told the Press Association: "He was always friendly, nothing to suggest (he was violent). He was normal, to be honest."

Abedi is believed to have attended the Manchester Islamic Centre, also known as the Didsbury Mosque.

Here, he reportedly caught the attention of one imam whom he stared down during a sermon denouncing terrorism.

"Salman showed me a face of hate after that sermon," Mohammed Saeed told The Guardian of the 2015 encounter.

"He was showing me hatred."

Fawaz Haffar, a businessman and trustee of the mosque, said he "probably" did attend there, given his father used to perform the call to prayer and his brother Ismail attended as a volunteer until recently.

He said: "I see him (the father) praying but I don't know really who he is. I see him sometimes raising the azan, or call to prayer, but that was a long time ago.

"As far as I knew he went back to Libya when things were much better over there, to work over there.

"He was devout as far as I know. He had three sons, one of them is detained, one of them is a suspect and the third one I have no idea who he is."

He said the mosque is moderate, modern and liberal and that he is a member of an organisation liaising with police, the Independent Advisory Group.

Abedi studied business and management at Salford University two or three years ago, a source said, but dropped out of the course and did not complete his degree.

The source said Abedi began his course in 2014 and attended lectures for two years but then stopped going.

He would have graduated this summer.

He did not live in university accommodation, had not been in any trouble at the university and was not on any radar for pastoral or social care.

It is understood Abedi was not known to have participated in any clubs or societies during his time in higher education - and never met with the resident imam.

Dr Sam Grogan, the university's Pro-Vice Chancellor Student Experience, said: "All at the University of Salford are shocked and saddened by the events of last night. Our thoughts are with all those involved, their families and their friends."

Libyan refugee Abdalraouf Abdallah was sentenced to five-and-a-half years in jail last year after helping Muslim convert and former RAF Iraq War veteran Stephen Gray try to get to Syria.

Abdallah, wheelchair-bound after he was shot in Libya in 2011, lived in Westerling Way, Moss Side, a short drive from Abedi's Elsmore Road address.

Abdallah came to the UK with his family as refugees in 1993.

Gray, who lived at nearby Whitnall Street in the city, was jailed for five years for terror offences, after he twice attempted to join jihadis in Syria.