Brentford have reportedly told Arsenal that they can only sign David Raya if they loan the goalkeeper back to them for the rest of the season.
The Gunners are seeking competition for Bernd Leno in goal after selling Emiliano Martinez to Aston Villa in a £20m deal earlier this week.
Raya has emerged as a possible option but, according to The Telegraph, Brentford have already knocked back a £10m bid from Arsenal.
Sky Sports News suggests that a transfer could still go through before the October 5 deadline, but only if Arsenal loan the Spaniard back to the promotion-chasing Bees for 2020-21.
Mikel Arteta's side are also believed to be in talks with Dijon keeper Runar Alex Runarsson, although that transfer is likely to be dependent on whether or not Raya joins.