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Saliba was withdrawn during the first half of France's semi-final clash with Spain, which saw Les Bleus go down 2-0.

The centre-back made six starts at the tournament, with four of those resulting in clean sheets for France. 

After Saliba's injury, it was reported that he could be sidelined for four or five months, which would represent a huge blow to Arsenal's hopes of retaining the Premier League title.

Though the Gunners did not announce a timeframe for Saliba's recovery, they confirmed that the 25-year-old must undergo a long rehabilitation process. 

"William Saliba has returned to us from World Cup duty, where he played an integral role in France reaching the semi-finals of the competition," a club statement said. 

"Subsequent specialist reviews on William's return to London this week have confirmed that he has suffered a back injury which will require a period of rehabilitation.

"Extensive assessments have concluded that surgery is not recommended, but William should now commence a managed recovery programme.

"William's rehabilitation will commence immediately, with continual management of his injury, and he is expected to be out of action for an extended period.

"Everyone is fully focused on supporting William to ensure he is back to full fitness as soon as possible."

Arsenal's Premier League campaign opens at home to newly promoted Coventry City on 21 August though it faces FA Cup winner Manchester City in the Community Shield five days earlier.

As news of Saliba's lay-off was confirmed, reports emerged that Mikel Arteta's side could turn to former City man John Stones as it looks to strengthen at centre-back.

Stones is a free agent after bringing an end to his 10-year stint at the Etihad Stadium, though he still impressed for England at the World Cup, appearing in five games as Thomas Tuchel's men finished third.