Hashem Abedi was allegedly plotting an attack after being aware of the Manchester attack carried out by his brother, Salman Mirror News Reports.
The kid brother of Manchester suicide-bomber Salman Abedi was planning his own atrocity, security sources fear.
Libyan security forces said Hashem was an Islamic State member and “was aware of all the details” of his brother's attack plans.
The arrest of Hashem took place in the capital Tripoli as he went to pick up cash transferred from his brother Salman.
Salman had transferred 4,500 Libya Dinar (£2,500) hours before he blew himself up.