Arsenal skipper Per Mertesacker has backed the club's decision to offer a contract extension to French centre-back Laurent Koscielny.

Earlier this month, Koscielny put pen to paper on a new deal which will keep him at the North London club until 2020.

"I've worked closely with Laurent ever since I arrived here and it's been great to witness his continued progression," Mertesacker told the matchday programme for Sunday's Emirates clash with Burnley.

"He's really developed his skills in so many areas - his defending, his communication and how he's handled becoming a key player for this club.

"It's an absolute joy to watch him play because he has all the ingredients to be a top defender, which he is.

"I'm just proud to be his team-mate and keeping him here was absolutely the best decision the club could have made."