Arsenal and St Étienne have reached a €30million agreement for the transfer of William Saliba, RMC reports.
Both clubs are however still in discussion over minor details, including bonuses and clauses.
The 18-year-old defender has already agreed a contract with Arsenal, but he will return to St Étienne on loan until the end of the 2019/2020 season.
Saliba was identified by Arsenal manager, Unai Emery, as a long-term replacement for Laurent Koscielny, who has a year left on his current deal at Emirates.
Emery is keen to strengthen his squad in this summer's transfer window, after finishing in fifth place on the Premier League table last campaign.
On the other hand, Saliba played a key role in helping Saint-Etienne secure fourth place in Ligue 1.