Hashem Abedi, 23, was found guilty in March of murder for encouraging and assisting his older brother Salman to plot the bombing at the Manchester Arena that killed 22 people.

The bombing occurred as parents arrived to collect their children at the close of a May 2017 show by the US pop singer.

Among the dead were seven children, the youngest aged just eight, while 237 people were injured. The attack was the deadliest in Britain since the 2005 London transport suicide bombings which killed 52 people.

Judge Jeremy Baker said the men were equally culpable and had deliberately targeted a concert attended by young people, with almost half those killed children or teenagers.

"The stark reality is that these were atrocious crimes: large in their scale, deadly in their intent and appalling in their consequences," Baker told London's Old Bailey court.

He jailed Abedi for life for murder and conspiracy to cause an explosion, and said he would serve at least 55 years behind bars.

Abedi was not in court for the sentencing hearing, having refused to enter the courtroom where distraught families of victims had given harrowing accounts of the devastating impact the bombing had had on their lives.

The Abedi brothers, born to Libyan parents who emigrated to Britain during the rule of late leader Muammar Gaddafi, had plotted the attack at their home in south Manchester, experimenting with the construction of a homemade device.

They made the device at a separate address in the city and then bought a car to store the bomb-making equipment, shortly before they returned to Libya in mid-April 2017.

Hashem remained in Libya while his 22-year-old brother carried out the bombing, but police said he persuaded acquaintances to buy chemicals to make the explosives and had sourced metal drums used to build prototype devices.

Hashem denied involvement but offered no evidence in his trial and a jury agreed he was as guilty as his brother of murder.

Australian Associated Press