Sunu spent last term, along with Francis Coquelin, under the stewardship of boss Christian Gourcuff and appears to have been released by Arsene Wenger having had limited first team opportunities.
The decision to loan Campbell to the Ligue 1 outfit has been forced on Arsenal after the 19-year-old failed in his attempt to seal the necessary work permit. The scenario precipitated the acquisition of Korean international Chu Young Park.
Henri Lansbury is another man who will garner further experience away from the Emirates. West Ham United have sealed a season-long loan deal for the England under-21 international and will help Sam Allardyce fill the vacuum left by the departed Scott Parker.
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