Teenage terrorists in the UK will face life sentences without parole under laws announced by Prime Minister Boris Johnson.
A trial judge was unable to sentence Hashem Abedi, 23, to a full-life term for his role in helping his suicide bomber brother Salman, who killed 22 people in Manchester.
Hashem was told he faced at least 55 years in prison but may eventually be released because he was 20 at the time of the bombing in May 2017.
Mr Johnson said the age at which a convicted killer can be considered for a full-life term would be reduced from 21 to 18, under plans to be published this week.
"Judges who want to impose tougher sentences have their hands tied by a complex system," Mr Johnson wrote in the Sunday Express.
“We’re going to remove a loophole that lets some truly despicable criminals avoid such a sentence because they’re under 21 at the time of their crime.
“If, like Manchester Arena bombing accomplice Hashem Abedi, you plot in a cold, calculating and deliberate manner to murder and maim dozens of people, then it doesn’t matter if you’re only 18, 19 or 20 when you do so.
“You’re an adult and a judge should have the power to keep you off the streets for life.
"And we’re going to lower the minimum age for whole-life sentences to 18 so that can happen.”
Hashem expressed no remorse for his role in the attack and refused to go to court when he was sentenced last month.
He is believed to have spoken with Salman just before he carried out the attack at Manchester Arena at the end of a concert by US singer Ariana Grande.
Hashem helped his brother to secure the ingredients for the home-made bomb but was in Libya at the time of the blast.
Manchester officials said it was “disappointing” that he could not be jailed for life, even though he would not be released until he was in his late 70s at the earliest.
Former justice minister David Gauke said the latest plans would only apply to a handful of people and were not a radical departure from current sentencing measures.
"Obviously they want to send a signal on tougher sentences,” Mr Gauke told Sky News.
“This is principally about sending a strong signal, particularly in light of the Manchester bombings case."
The announcement is the latest measure announced by the government to toughen sentences for terrorists.
It had come under pressure to act after a man released early from a jail term for terrorism killed two people at a rehabilitation conference in London.
Usman Khan was freed half-way through a 16-year term for plotting to blow up London’s stock exchange before carrying out the knife attack in central London in November last year.
He was shot dead by police after stabbing five people, killing two.
The attack led to authorities reviewing the status of dozens of released terrorists.
Mr Johnson said that the early release programme would end for terrorists.