Het Nieuwsblad says the Gunners are looking to replace the departed Thomas Vermaelen and Alderweireld appeals due to his age and ball-playing ability.
The 25-year-old's dad Vic, who is also his agent, used an interview last week to indicate that a loan spell away from Atletico could be on the cards.
He said: "Toby wants to play, going out on loan would be the best option. If there is a solution, Atletico won't stand in his way.
"Since last year, we've had several discussions on this issue and Atletico understands that we don't think it makes sense to leave Toby on the bench for another year."
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