The 27-year-old has vowed to never play for the Portuguese champions again following a huge falling out with the club president regarding a “gentleman’s agreement” over his sale this summer.
Gyokeres was under the impression he would be able to leave Sporting for a fee of around €65 million but the club are now demanding €70 million plus another €10 million in bonuses, which Arsenal are yet to reach.
According to The Guardian, Sporting are now considering internal action against the Sweden international after he failed to show up to training on Saturday.
Club officials are awaiting an official explanation from Gyokeres to justify his absence whether due to a medical condition, an approved personal leave extension, or a family emergency.
If no valid reason is provided, the Portuguese club is expected to issue a fine.
Arsenal remain in contact with the club and player and are understood to be planning an improved offer in the near future.