Security forces arrested the father and younger brother of the suicide bomber in Libya while British police arrest a seventh suspect.
More arrests have been made in connection with the deadly suicide bomb attack at a concert venue in Manchester. The attack was claimed by Daesh.
At least 22 people were killed and dozens others wounded when a suicide bomber blew himself up at the end of a concert by US singer Ariana Grande outside the Manchester Arena.
The father and younger brother of suicide bomber, Salman Abedi, have been arrested in Libya's capital city of Tripoli, while British police arrested a seventh person in connection with Monday's bombing.
A counter-terrorism force detained the father, Ramadan Abedi, outside his home in the Tripoli suburb on Wednesday, while the bomber's younger brother Hashem Abedi, was arrested on Tuesday.
Meanwhile in Britain, British police said they had arrested a seventh person following searches at an address in Nuneaton, central England.
"As it stands, six men and one woman have been arrested in conjunction with the investigation and remain in custody for questioning," a British police statement said.
Britain's official terror threat level has also been raised to "critical", the highest level, late on Tuesday.
TRT World's Jon Brain reports on the latest from Manchester.
Britain's home secretary criticised US officials for leaking sensitive information about the ongoing inquiry into the bombing.
Amber Rudd told Sky News that US officials provided information to media that Britain preferred to keep confidential for reasons of operational security.
Grande has cancelled all her shows through to June 5.