Arsenal manager Arsene Wenger has confirmed Jack Wilshere will yet again spend a spell on the sidelines after suffering a hairline crack in his fibula during an accidental collision in training.

After the England international missed the Community Shield victory against Chelsea on 2 August, the French boss claimed it was just a minor ankle issue and that he would be available "within a matter of days".

"He couldn't take part in the game today because of an ankle problem he sustained yesterday. It happened at the training ground. We don't think it's bad at all but I haven't been told whether it will be two days or five days. I don't know how long he will not be available for. It's a matter of days," Wenger said after the Wembley game.

But Mirror reported later that the midfielder could be out for as much as eight weeks after scans suggested the injury was worse than initially predicted.

And Wenger has now confirmed the bad news in a statement to the club's official website.

"The information you have heard about Jack Wilshere is right. I had a bad surprise because it is a hairline crack in his fibula that gives him a few weeks out," the manager said.

"There is minimal damage apart from the bone damage – there is no damage at all apart from that. It was a collision in training and it was all completely accidental."

Meanwhile, Wenger has expressed his delighted after the club announced key players Santi Cazorla and Theo Walcott have committed their futures to the North London side with new deals.

"I'm very happy because, first of all, they are two exceptional players, and because I think the cohesion inside the club is an underestimated quality," the manager told Arsenal Player.

"To have a good cohesion level, it's important that your players stay together for a long period. That they will contribute. You see how people chant Santi's name. Santi is technically perfect, he's a very intelligent player and a very good team player as well.

"Theo is a good goalscorer and he makes very intelligent runs. I think he's at a moment of his career where he knows that it's now time for him to completely fulfil his potential."