The Belarus international completed his protracted move to the Camp Nou last week for a fee reported to be in the region of €15million (£11.9million).

Hleb joined The Gunners from Stuttgart in 2005 but grew unsettled in north London during the latter stages of his time at Emirates Stadium.

The 27-year-old, currently with his Barca team-mates on their pre-season tour in Scotland, hailed Arsenal manager Arsene Wenger on Wednesday, stressing the key role he plays in driving the club forward.

And Hleb has now warned the club that they face testing times when Wenger leaves his post in the future.

"Wenger is everything to Arsenal," he told The Daily Telegraph, "The future for Arsenal, if Wenger stays, is that they will always play at the top.

"But of course it is difficult now because Arsenal have a few political differences. When he leaves, I think this is a difficult time coming for Arsenal."

Hleb also said it would be 'fantastic' if he were joined at Barcelona by Cesc Fabregas and the reportedly unsettled Emmanuel Adebayor, while he also questioned Arsenal's policy over sales.

"These are fantastic players, Adebayor and Cesc," Hleb continued. "Every team would like to keep these players. For me it would be fantastic if they came to Barcelona.

"Those players would bring good energy and power to this club. For Barcelona, it would be fantastic, and for me personally as well, if they leave.

He added: "Sometimes I think that Arsenal do not want to keep this team, not give something more."