Former Arsenal centre-back Martin Keown has urged the club to sign defensive back-up while adding Arsene Wenger must look to bolster his forward line ahead of the new season.

Bacary Sagna is expected to leave the Gunners for Manchester City, while the future of club captain Thomas Vermaelen is also uncertain after being marginalised from the first team at the Emirates Stadium.

In addition, Olivier Giroud was overstretched in Arsenal's attack last season, despite scoring 22 goals in 50 appearances in all competitions and while Keown says strengthening the back four should be the priority he admits Wenger will have a dilemma come the summer.

"It is paramount the club kept Arsene Wenger," he told Sky Sports News Radio. "He is great to work with, very much in charge – he likes to take charge of the training, the organisation, the team selection and planning for the future.

"There are some purchases needed. In the defensive areas, if Sagna goes and Vermaelen leaves there is money to spend in the defence, which he won't want to do.

"He'll want to spend the money in the final third because Giroud needs help in that area. There is no big panic, he'll manage it in the same way as always but maybe with a slight more urgency.

"The clock is ticking for all of us. He's been there a long time but I still think there is a lot to achieve."

Giroud, who is hopeful of leading France's attack at the upcoming Word Cup finals, says the club will sign a new striker in the summer transfer window after the departure of both Nicklas Bendtner and Park Chu-Young.

"I can tell you Arsenal will add a striker to the team," he told InfoSport+. "We need another striker. Great clubs have several good strikers, who compete with each other."

The news has worked to swell rumours regarding Arsenal's pursuit of Real Sociedad forward Carlos Vela, with the club deep in negotiations with over activating his release clause.