"We will not extradite Hashem Abedi to UK authorities," Ahmad Ben Salim, spokesperson of the Deterrence Force, a counterterrorism group in Tripoli, was quoted as saying by Reuters.
However, later in the day, Libyan militia that is holding the brother of the Mancheter Arena suicide bomber has voiced readiness to cooperate if Attorney General approved the UK extradition request.
Abedi, who is currently believed to be held by the group, is suspected of a conspiracy to cause the explosion outside the Manchester Arena.
The spokesperson said that Britain and the Deterrence Force has no legal agreement that would allow for the extradition of the suspect.
According to Manchester police, a warrant for the arrest of Salman Abedi’s sibling was submitted on Wednesday to the Libyan authorities.
In late May, an explosion occurred outside the Manchester Arena after US pop singer Ariana Grande's concert ended, leaving 22 people dead and some 120 injured. UK police have identified 22-year-old Salman Abedi as the suspected perpetrator of the attack, which was claimed by Daesh.