It is understood the deal agreed between the clubs is an initial loan with an obligation to buy next summer dependent on certain achievable conditions.
The French midfielder, who joined Arsenal from Lorient in 2018, spent last season out on loan at Hertha Berlin, making 24 appearances and scoring two goals before injury cut his campaign short.
Arsenal centre-back William Saliba looks set to join him at Marseille on loan as a result of club’s pursuit of Ben White.
After talks with technical director Edu and Arteta, it has been decided his development would be best served with another loan spell.
Saliba has made 31 league starts in the last two seasons on loan at Saint Etienne and Nice but Arsenal feel he needs a full season playing before being integrated into their first-team plans.
This is a breaking news story that is being updated and more details will be published shortly. Please refresh this page for the latest updates.
Sky Sports brings you live updates as they happen. Get breaking sports news, analysis, exclusive interviews, replays and highlights.
Sky Sports is your trusted source for breaking sports news headlines and live updates. Watch live coverage of your favourite sports: Football, F1, Boxing, Cricket, Golf, Tennis, Rugby League, Rugby Union, NFL, Darts, Netball and get the latest transfers news, results, scores and more.