Hleb left the Gunners to join Barcelona in 2008, but failed to make an impact for the Spanish side.
Hleb admitted: “Of course it is my fault I left Arsenal but this has happened.
“Not a lot of players say no to Barcelona but if I had known before what would happen of course I wouldn’t have gone.
“I won the Champions League with Barcelona in 2009 but I didn’t play a lot. I lost a bit of my form and confidence.”
Hleb joined Birmingham this summer after turning down moves to Spurs and Liverpool.
He added: “I made a decision to come to Birmingham.
“I decided for one year to come back to the Premier League where I am very happy and want to take this chance.”
