The 33-year-old, who has been linked with a return to France, refused to travel with the Gunners squad for their pre-season tour of the US
The 33-year-old is keen to return to France after nine season with the Gunners, having joined in a £9.7million deal from Lorient in 2010.
The Evening Standard claim Koscielny’s request to be released from his contract – a year before it expires – was rejected by club chiefs, prompting him to go AWOL.
In a brief statement, Arsenal said they were ‘very disappointed’ by their club captain’s actions.
Below, talkSPORT.com list six possible replacements for Koscielny.
William Saliba (Saint-Etienne)
Arsenal are believed to be on the verge of completing a £27million deal for Saint-Etienne starlet Saliba.
Unai Emery is planning to loan him back to the French club, but that decision could change with Koscielny’s uncertain future.
Saliba made 16 Ligue 1 appearances in an impressive 2018/19 breakthrough season.
The 18-year-old could be an ideal replacement for Koscielny.
Gary Cahill (unattached)
Arsenal have been linked with a summer move for Cahill, who is a free agent after leaving Chelsea last month.
The defender, who won every major honour with the Blues, would replace the experience lost if Koscielny does leave.
Cahill insists he is still fit despite starting just six games last season.
In May, he told talkSPORT: “I’m fit as a fiddle and ready to go. I’ve used the time I’ve not been playing wisely.
“This chapter will close and another will open for me without a doubt, so I have a few more years left to play.”
Krystian Bielik (Arsenal)
Bielik has more or less given Arsenal an ultimatum: Play me or sell me.
The Poland Under-21 international has said he has no interest in returning to Arsenal’s Under-23 side and wants to continue playing senior football.
Bielik impressed in midfield and defence in a loan spell with Charlton as he helped Lee Bowyer’s side win promotion to the Championship last term and he then starred at the European Under-21 Championship.
At just 21 years old, Arsenal could turn to Bielik, who is attracting interest from AC Milan, to address their defensive woes.
Samuel Umtiti (Barcelona)
Umtiti has struggled with injuries since playing a crucial role in France’s World Cup triumph last summer.
A knee injury, which required surgery, has seen the Frenchman lose his starting place to countryman Clement Lenglet.
Arsenal have been long-term admirers of Umtiti, who has been linked with a big-money move to Paris Saint-Germain.
If he is surplus to requirements at the Nou Camp, Arsenal would be wise to make a move.
Eric Bailly (Manchester United)
Arsenal reportedly had an approach rejected for Bailly in January.
The Ivory Coast defender was used sparingly by Manchester United boss Ole Gunnar Solskjaer before a knee injury in April ended his season.
With United targeting a centre-back in this summer’s transfer window, Bailly’s Old Trafford days appear to be numbered.
While it is unlikely that the Red Devils would sell one of their players to a direct rival, Arsenal would offer Bailly a fresh start.
Toby Alderweireld (Tottenham)
Tottenham are helpless to stop Alderweireld from leaving if a club activates his release clause this summer more than two weeks before the start for the season.
The 30-year-old has one year left on his contract and could leave for just £25m.
Last week, shock reports claimed Arsenal were considering a move for Alderweireld.
Given the Gunners’ financial restraints, Alderweireld would be excellent value for money.
However, joining Tottenham’s fierce rivals would not go down well with the club’s fans.
Alderweireld would be the first player to move from Tottenham to Arsenal since Sol Campbell’s controversial switch in 2001.