MANCHESTER — The suspect in the deadly Manchester concert bombing was driven by what he saw as unjust treatment of Arabs in Britain, a relative said Thursday (May 25), confirming he made a final phone call in which he pleaded: “Forgive me”.

Salman Abedi was particularly upset by the killing last year of a Muslim friend whose death he believed went unnoticed by “infidels” in the UK, said the relative, speaking on condition of anonymity over concerns for her own security.

“Why was there no outrage for the killing of an Arab and a Muslim in such a cruel way?” she asked. “Rage was the main reason,” for the blast that killed 22 at the end of an Ariana Grande concert at Manchester Arena on Monday, she said, speaking by telephone from Libya.

The new insight into Abedi’s motivation came as Britons faced stepped-up security, authorities pushed forward with raids and the investigation extended across Europe into Libya, where most of the suspected bomber’s family lived.

The number of arrests in the UK ticked up to eight as British Transport Police said armed officers would begin patrols on some trains because of an increased threat of terrorism. Greater Manchester Police Chief Constable Ian Hopkins said, without elaborating, that searches of suspects’ homes brought “very important” clues in the probe of the bombing. But leaks from the investigation were creating a trans-Atlantic diplomatic mess.

Manchester police halted their sharing of investigative information with the US through most of Thursday until receiving fresh assurance there would be an end to leaks to the media.

British Prime Minister Theresa May, who spoke about the matter with US President Donald Trump at a NATO summit in Brussels, said the countries’ partnership on defence and security was built on trust. But “part of that trust is knowing that intelligence can be shared confidently”, she said.

Mr Trump pledged to “get to the bottom” of the leaks, calling them “deeply troubling” and asking the Justice Department and other agencies to “launch a complete review of this matter”.

British officials were particularly angry over photos published by The New York Times showing remnants of a blue backpack which may have held the explosive. But it wasn’t clear US officials were the source of the images, which the Times defended as “neither graphic nor disrespectful of victims” and consistent with basic reporting “on weapons used in horrific crimes”.

British security services were also upset that 22-year-old Abedi’s name was apparently leaked by US officials while police in the UK continued withholding it and while raids were underway in Manchester and in Libya. Mr Hopkins said the leaks “caused much distress for families that are already suffering terribly with their loss”.

Meanwhile, the investigation into the blast widened.

Authorities chased possible links between Abedi and militants in Manchester, elsewhere in Europe, and in North Africa and the Middle East. They were exploring potential ties to Abdalraouf Abdallah, a Libyan jailed in the UK for terror offences, and to Raphael Hostey, an Islamic State recruiter killed in Syria.

Abedi’s family remained a focus, too, with a brother in England, his father and another brother in Libya among those detained. Abedi’s father was allegedly a member of the al-Qaeda-backed Libyan Islamic Fighting group in the 1990s — a claim he denies.

An emerging portrait of the bomber remained complicated by competing assessments over whether Abedi held views that had sparked concern before the bombing.

Mr Akram Ramadan, a member of the Libyan community in Manchester who attends the city’s Didsbury Mosque, said Abedi was banned from the mosque after he allegedly interrupted an imam’s anti-Islamic State sermon.

“He stood up and started calling the imam — ‘You are talking bollocks’,” Mr Ramadan said. “And he gave a good stare, a threatening stare into the imam’s eyes.”

Mr Mohammed Fadl, a community leader, rejected that account. While Abedi’s family was well-known in Manchester, Abedi himself did not attend many gatherings, Mr Fadl said.

However, Mr Fadl said he had heard Abedi’s father took his son’s passport away over concerns about his ties to alleged extremists and criminals.

“Very few people in the community here were close to him, and therefore Salman’s fanaticism wasn’t something the community was aware of,” he said.

Mr Ahmed bin Salem, a spokesman for the Special Deterrent Force in Libya, said Abedi placed his final call to both his mother and a brother. Abedi’s relative said he had spoken with his brother only, asking that his message be relayed to his mother.

“He was giving farewell,” Mr bin Salem said.

Abedi’s relative said the suspected bomber was pained by the killing of Abdel-Wahab Hafidah, an 18-year-old who news reports say was chased by a group of men, run over and stabbed in the neck in Manchester in May 2016.

“They wouldn’t let you share bread with them,” she said Abedi told her. “They are unjust to the Arabs.”

Mr Bin Salem said Abedi’s mother told investigators her son left for the UK four days before the attack after spending a month in Libya. Based on the account from a younger brother, investigators think Abedi used the internet to learn how to make a bomb and “seek victory for the Islamic State”, Mr bin Salem said.

The allegations clashed with what Abedi’s father said a day earlier in an interview with the AP. “We don’t believe in killing innocents,” Mr Ramadan Abedi said before he was detained in Tripoli.

Around the UK, many fell silent Thursday for a late-morning minute in tribute to the victims.

In Manchester’s St Ann’s Square, where a sea of floral tributes grew by the hour, a crowd sang the hometown band Oasis’ song Don’t Look Back in Anger. Queen Elizabeth II visited victims of the attack at Royal Manchester Children’s Hospital, telling 14-year-old Evie Mills and her parents: “It’s dreadful. Very wicked, to target that sort of thing.”

Fifteen-year-old Millie Robson, wearing one of Grande’s T-shirts, told the queen she had won VIP tickets to the pop star’s concert. She recalled leaving the concert when the blast struck and remembered an intense ringing in her ears, but not being entirely aware that she was bleeding badly from her legs.

The teenager credited her father’s quick action in picking her up and tying off her wounds to stem the bleeding.

“Compared to other people I’m quite lucky really,” she said.

In addition to those killed, 116 people received medical treatment at Manchester hospitals for wounds from the blast. The National Health Service said 75 people were hospitalised. AP