The Manchester bomber’s brother has said he was radicalised in the UK two years before he launched a terror attack in the name of Isis.

Libyan officials said Hashem Abedi, who was arrested in Tripoli following the atrocity, also confirmed British police claims he brought materials for his device in the UK.

Ahmed bin Salem, a spokesperson for the Government of National Accord’s counter-terror force, said Hashem admitted knowing of his brother’s plans but did not know where they would be carried out.

​Salman Abedi killed 22 people, including seven children, when he detonated a homemade bomb amid Ariana Grande fans leaving a concert at Manchester Arena.

“Hashem said that he and Salman got the ideology of Daesh [Isis] in Manchester in 2015 from the internet and some friends in the UK,” said Mr bin Salem.

“He added that they used to watch videos and had sympathy for children in Syria and wanted to do something for Daesh to help.”

Manchester bomber Salman Abedi's cousins speak out

Officials said the two British brothers flew to Libya, where their parents were originally from , on 18 April but Salman left around a week before the attack while claiming he was going on a pilgrimage to Mecca.

Abedi flew to Turkey but then doubled back across Europe, flying via Dusseldorf to arrive in Manchester on 18 May.

Hashem said “all necessary things” were purchased for the bomb in Britain.

Experts told The Independent the deadly device could easily have been constructed in the four days between Abedi returning from Libya and launching the attack, with Greater Manchester Police saying the bomber made “core purchases” himself.

He phoned Tripoli before the attack to “say goodbye to his family”, Mr bin Salem said, adding: ”Salman phoned Hashem's phone on the day of the attack to talk with his family.

“The mother had refused to talk with him because they were angry with him as he lied.

“Hashem knew about the attack and convinced his mother to talk to him.”

Manchester explosion in pictures Show all 37 1 /37 Manchester explosion in pictures Manchester explosion in pictures People running down stairs as they attempt to exit the Manchester Arena after a blast, where U.S. singer Ariana Grande had been performing, in Manchester Twitter/@ZACH_BRUCE/ via REUTERS Manchester explosion in pictures Helpers attend to people inside the Manchester Arena after a suspected suicide bomber detonated an explosive device at the end of an Ariana Grande concert, killing 22 people PA wire Manchester explosion in pictures Armed officers guard outside a hotel near the Manchester Arena following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Police officers are seen outside the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester, northern England Reuters Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - Emergency services arrive close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area. (Photo by Dave Thompson/Getty Images) Getty Images Manchester explosion in pictures MANCHESTER, ENGLAND - MAY 23: Police escort members of the public from the Manchester Arena on May 23, 2017 in Manchester, England. An explosion occurred at Manchester Arena as concert goers were leaving the venue after Ariana Grande had performed. Greater Manchester Police have confirmed 19 fatalities and at least 50 injured. (Photo by Christopher Furlong/Getty Images) Getty Images Manchester explosion in pictures Medics deploy at the scene of a reported explosion during a concert in Manchester, England on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area / AFP PHOTO / Paul ELLIS (Photo credit should read PAUL ELLIS/AFP/Getty Images) AFP/Getty Images Manchester explosion in pictures Police and fans close to the Manchester Arena, after reports of an explosion Getty Images Manchester explosion in pictures There have been reports of explosions at Manchester Arena where Ariana Grande had performed Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England, at a concert in Manchester Arena AFP/Getty Images Manchester explosion in pictures Police stand by a cordoned off street close to the Manchester Arena Getty Images Manchester explosion in pictures Police deploy at scene of explosion in Manchester, England AFP/Getty Images Manchester explosion in pictures Police deploy at scene of a reported explosion during a concert in Manchester, England, on May 23, 2017. British police said early May 23 there were "a number of confirmed fatalities" after reports of at least one explosion during a pop concert by US singer Ariana Grande. Ambulances were seen rushing to the Manchester Arena venue and police added in a statement that people should avoid the area AFP/Getty Images Manchester explosion in pictures An ambulance drives away from the Manchester Arena, where U.S. singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures Police escort members of the public from the Manchester Arena in Manchester, England. Getty Images Manchester explosion in pictures A woman sits in the street in a blanket near the Manchester Arena as police guard the area following reports of an explosion, in Manchester, Britain EPA Manchester explosion in pictures Two women wrapped in thermal blankets stand near the Manchester Arena, where US singer Ariana Grande had been performing, in Manchester Reuters Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester. At least 19 people have been confirmed dead and others 50 were injured, authorities said. It is being treated as a terrorist incident until police know otherwise EPA Manchester explosion in pictures A Royal Logistic Corps (RLC) bomb disposal robot is unloaded outside the Manchester Arena following reports of an explosion, in Manchester EPA Manchester explosion in pictures Members of the public receive treatment from emergency service staff at Victoria Railway Station close to the Manchester Arena on May 23, 2017 in Manchester, England. There have been reports of explosions at Manchester Arena where Ariana Grande had performed this evening. Greater Manchester Police have have confirmed there are fatalities and warned people to stay away from the area Getty Images Manchester explosion in pictures Armed police after a suspected terrorist attack at the Manchester Arena at the end of a concert by US star Ariana Grande left 19 dead PA wire Manchester explosion in pictures Emergency services arrive close to the Manchester Arena in Manchester Getty Images Manchester explosion in pictures An amoured police vehicle patrols near Manchester Arena in Manchester Getty Images Manchester explosion in pictures A man carries a young girl on his shoulders near Victoria station in Manchester AFP/Getty Images Manchester explosion in pictures Police officers stand at the Miller Street and Corporation Street Crossroads, in front of the Manchester Arena in Manchester, England Getty Images Manchester explosion in pictures Police block a road near to the Manchester Arena in central Manchester, England AP Manchester explosion in pictures Armed police patrol near Victoria station in Manchester, northwest England. Twenty two people have been killed and dozens injured after a suspected suicide bomber targeted fans leaving a concert of US singer Ariana Grande in Manchester Getty Images Manchester explosion in pictures Police forensic officers leave the Manchester Arena as they investigate the scene of an explosion in Manchester Getty Images Manchester explosion in pictures A forensic officer collects evidence on a walkway between Victoria station and Manchester Arena following a deadly terror attack in Manchester, Getty Images Manchester explosion in pictures A woman and a young girl wearing a t-shirt of US singer Ariana Grande talks to police near Manchester Arena following a deadly terror attack in Manchester, Getty Manchester explosion in pictures epaselect epa05982725 Susan Walton and daughter Katie, 10 (pictured), who attended the concert of Ariana Grande at the Manchester Arena, are seen in Manchester, Britain, 23 May 2017. According to a statement released by the Greater Manchester Police on 23 May 2017, police responded to reports of an explosion at Manchester Arena on 22 May 2017 evening. At least 19 people have been confirmed dead and around 50 others were injured, authorities said. The happening is currently treated as a terrorist incident until police know otherwise. According to reports quoting witnesses, a mass evacuation was prompted after explosions were heard at the end of US singer Ariana Grande's concert in the arena. EPA/NIGEL RODDIS EPA Manchester explosion in pictures Mayor of Greater Manchester Andy Burnham and Manchester City Council Leader Sir Richard Leese speak to the media outside Manchester Town Hall after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Dave Higgens/PA Wire Manchester explosion in pictures The media gather behind a police cordon in Manchester Getty Images Manchester explosion in pictures Flowers left close to the Manchester Arena, the morning after a suicide bomber killed 22 people, including children, as an explosion tore through fans leaving a pop concert in Manchester Danny Lawson/PA Wire Manchester explosion in pictures Ariana Grande concert attendees Karen Moore and her daughter Molly Steed, aged 14, from Derby, leave the Park Inn where they were given refuge after last night's explosion at Manchester Arena Getty Manchester explosion in pictures Signs saying 'We love Manchester' are displayed in a window in Manchester, England Getty Images

Abedi’s mother told investigators her son had “asked for forgiveness” but she had not understood why at the time.

It was not possible to verify what conditions the Abedis were questioned under or whether they had access to legal representation, although British consular officials have been granted access.

Libya’s Special Deterrence Force (Rada) previously said Hashem had been plotting an attack in Tripoli, and told investigators he spent time in Germany working as a driver between December last year and his return in April.

Hashem and his father Ramadan, who moved the family back to the Libya following the outbreak of the country’s civil war, remain in custody after being arrested by police in Tripoli.

​Abedi’s mother said both sons had been taken to the frontlines of the conflict as Ramadan fought against Muammar Gaddafi’s forces.

Sources with knowledge of the investigation told The Independent that Abedi developed extremist beliefs while in Manchester, but that the violence he was exposed to in Libya was a key part of the path to launching the attack.

He was known to security services as an associate of Isis recruiter Raphael Hostey, also from the city, who was killed in a drone strike in Syria last year.

Ramadan Abedi, the father of Salman Abedi (Reuters ) (Reuters)

Other prolific militants from Manchester include Abdalraouf Abdallah who was jailed last year for attempting to help fellow jihadis reach Isis territories in Syria after being shot and paralysed during the Libyan uprising.

Abedi also reportedly met Isis-linked fighters in the Katibat al-Battar al-Libi group during his visits to Tripoli and the coastal city of Sabratha.

A retired European intelligence officer told the New York Times that Abedi kept in contact with the militants after returning to Manchester.

Members of the group, which was originally formed by Libyan jihadis fighting in Syria in 2012, include Paris attacks ringleader Abdelhamid Abaaoud.

Battar brigade fighters who moved back to Libya set up terror training camps, with the Isis gunman who killed 30 British tourists on a beach in Tunisia among their graduates.

Europol has warned Libya could develop into a “second springboard” for Isis attacks in the EU and the North Africa as the group loses territory in Syria and Iraq.

Abedi had a “relatively minor” criminal record as a teenager but was not known to police for holding extremist views, appearing on police logs in 2012 over offences of theft, receiving stolen goods and assault.

A CCTV image dated 18/5/2017 showing Salman Abedi before he carried out the Manchester attack (Greater Manchester Police)

Acquaintances said he was previously linked to gangs, smoked cannabis and drank but came back from Libya a “completely different guy”, later hanging a black Islamist flag from his home and referring to Brits as “infidels” who were “unjust to Arabs”.

The same transformation has been documented in many of Europe’s deadliest terrorists, including petty criminals and drug dealers in the Isis “super cell” behind the Paris and Brussels attacks.

Nine suspects remain in custody over the attack in the UK, where a 20-year-old man was arrested on suspicion of terror offences after handing himself into police on Wednesday.

Two of the other arrests came on Tuesday, with a 20-year-old being held in Harpurhey, and a 38-year-old being detained at Heathrow Airport as part of a planned operation, both on suspicion of terrorism offences.

Police have released 12 people without charge, including an 18-year-old man understood to be Abedi's cousin and his older brother, Ismail.

Greater Manchester Police said they had found “significant evidence” in a car where Abedi may have stored items used to assemble his improvised explosive device.

The inquests into the deaths of the victims, who include seven children, are due to begin on Friday at Manchester Civil Justice Centre.