SAO PAULO, Nov 27 (Reuters) - Brazilian retailer GPA has agreed to sell its 34% stake in e-commerce firm Cnova to its French controller Casino, it said in a securities filing on Monday, concluding talks that had started in September.

GPA said its board of directors had approved the French retailer's 10 million-euro ($10.91 million) offer for the Cnova stake. Casino, which already holds a majority share of the e-commerce company, will increase it to 98.8% following the deal. ($1 = 0.9168 euros) (Reporting by Gabriel Araujo; Editing by Steven Grattan)