Arsenal manager Arsene Wenger confirmed on Thursday that he has agreed to trigger a one-year contract extension for captain Per Mertesacker.

Mertesacker has yet to play for Arsenal this term after suffering a serious knee injury in a pre-season friendly against Lens.

The 32-year-old defender's current deal was due to expire at the end of the season and, despite being someway from full fitness after knee surgery, Wenger wants to keep the World Cup winner for another 12 months.

"He has an option that we have taken. There was no negotiation, there was just an option that we took up. He is back in training, not with the squad but I think he is a few weeks away," Wenger told reporters.

Mertesacker replaced Mikel Arteta as the club's skipper after the Spaniard retired at the end of last season and took up a coaching role at Manchester City.

Arteta was sidelined with a number of injuries for much of his spell with the armband, but Wenger insists the same fate will not befall his current captain.

"It's completely accidental," he said of the German's knee problem.

"With Arteta, it's true that he struggled with muscular problems, but Per was accidental.

"It was a knee problem but he has recovered from that, so there's no reason why he should be injured again."