A cousin of Manchester bomber Salman Abedi had previously posted antisemitic messages on social media and voiced his hatred for the UK.
Abderahman Forjani, 21, was arrested last Tuesday along with his brother Abdalla,24, following the Manchester Arena atrocity on Monday night.
But in a series of posts revealed by The Times the younger of the two brothers had earlier shown his feeling towards Jews writing: “If only Hitler was still alive –these Jews would be burnt in chambers.”
Mr Forjani, who lives at the family home in Fallowfield, had also expressed his hatred towards his home city writing:”Manchester is my no.1 enemy I f***ing hate the s***hole.”
The barber shop that the two brothers ran called Fade Away was raided by police on Friday.
The duo’s 18 year old brother Alharth Forjani was also arrested.
It also emerged on Monday that the Manchester bomber had prayed at Didsbury mosque, in south Manchester, which was attended by at least two British members of Islamic State who had travelled to Syria.
Salman Abedi’s father Ramadan led the call to prayer at the mosque.
Last week the trustees of the mosque released a statement condemning the bombing and revealed that Abedi had clashed with the imam after he spoke out against Islamic State in 2015.