“Forgive me.”

These were among the final words that Manchester terror suspect Salman Abedi delivered to his family before allegedly bombing a pop concert attended by thousands of children.

The attack killed 22 and injured more than 100, while about 20 victims continue to battle life-threatening injuries in hospital.

Libya’s Special Deterrent Force spokesman Ahmed bin Salem, told UK newspaper The Times that Abedi called his mother and a brother 15 minutes before the blast.

“He was giving farewell,” Mr bin Salem told the paper.

But one of Abedi’s relatives told the Associated Press he had only spoken with his brother, requesting him to relay the message to his mother.

Mr bin Salem said the 22-year-old’s mother told investigators Abedi had spent one month in Libya and returned to the UK four days before the bombing.

A relative of Abedi’s, who wished to remain anonymous, said that in his final phone call, he pleaded “Forgive me”, AP reported.

The development came as a 10th suspect was arrested on Friday (AEST).

The source said he was particularly grief-stricken by an incident last year in which a Muslim friend of his, 18-year-old Abdel-Wahab Hafidah, died after being run down by a car and then stabbed in Manchester.

The relative claimed Abedi believed the killing went unnoticed by “infidels” in the UK.

“Rage was the main reason,” she said of Abedi’s motivation, speaking to AP by telephone from Libya.

“Why was there no outrage for the killing of an Arab and a Muslim in such a cruel way?”

She said Abedi had told her: “They (the British) wouldn’t let you share bread with them … They are unjust to the Arabs.”

Based on the account of Abedi’s younger brother, investigators believe the suspected bomber taught himself how to make a bomb on the internet and that he wanted to “seek victory for the Islamic State,” Mr bin Salem said.

In an interview with The Wall Street Journal, Abedi’s sister, Jomana, said her brother was “kind and loving”.

Ms Abedi said she was surprised by his atrocity in Manchester and believes he may have acted in response to what he saw as “injustices”.

“I think he saw children—Muslim children—dying everywhere, and wanted revenge,” she told the WSJ.

“He saw the explosives America drops on children in Syria, and he wanted revenge.

“Whether he got that is between him and God.”

A family friend, who spoke to the WSJ, said Abedi told his parents in Libya he was leaving to go on a pilgrimage to the Muslim holy city of Mecca within a week of the bombing.

The source said Abedi had also travelled to Libya in 2011 as a teenager to fight alongside his father in a militia, the Tripoli Brigade, to help depose the country’s former leader Colonel Muammar Gadhafi.

In 2014, Abedi and his mother moved back to Britain, where he was born, the family friend said.

Abedi remained in Manchester while both of his parents returned to Libya in October 2016, a relative told the WSJ.

Akram Ramadan, a member of the Libyan community in Manchester, alleged that Abedi had been banned from a local mosque after allegedly interrupting an imam’s anti-Islamic State sermon, saying “You are talking bollocks”.

Abedi’s father and brother are among suspected accomplices who have been arrested since the Ariana Grande concert attack.

In an interview before being detained, his father Ramadan Abedi told the AP: “We don’t believe in killing innocents. This is not us.”