The Premiership side's website said that the 21-year old midfielder signed the contracts and passed the medicals.

"Samir has shown great potential with his performances for Marseille and the French national team over the past two seasons and he will add great quality to our squad," the Gunners boss Arsene Wenger said.

"He is young, quick and technically an outstanding player."

Nasri has been voted France’s hottest prospect in 2006/2007 and was also Marseille's Player of the Year last season.

“This is a very important step in my life as a football player because Arsenal is a massive club," the France international said.

"I really hope everything will go well for me here. I will my best for Arsenal and its fans and I am honoured to be part of such a great football club."

Nasri is Wenger’s first summer signing and is seen as a perfect replacement for Alexander Hleb who moved to Barcelona.