Libyan Interior Minister Fathi Bashagha told CNN that the man, named Hashem Abedi, had been extradited on Wednesday.
Attacker Salman Abedi detonated a bomb at the end of Grande’s concert, as thousands of people were leaving the packed arena.
Many of the victims were teenage fans, the youngest among them was 8-year-old Saffie Rose Roussos.
The extradition came after police issued Hashem with an arrest warrant for murder, attempted murder and conspiracy to cause an explosion likely to endanger life, Greater Manchester Police said in a statement.
Chief Constable Ian Hopkins said Hashem had been handed over to British police officers on Wednesday morning.
Hashem was arrested shortly after the concert bombing, Reuters reported, as Libya’s counter-terrorism and anti-crime force Rada suspected he may have helped plan the attack.
The two brothers grew up in Manchester with parents who had fled Libya under the late Moammar Gadhafi. Their father, Ramadan, had returned to Libya in 2011 after rebels overthrew the government. His wife joined him in early 2017.
The brothers traveled to Libya together in April 2017. However, after three weeks, Salman returned to the UK and within days, launched his attack on the Manchester Arena.