The Dutchman made his stance clear over the delay tactics on show, warning Barkley that he has until this weekend to put pen to paper or else he will be offloaded.
Koeman has confessed that he is not confident of seeing the 23-year-old commit in the coming days, amid rumoured interest from Tottenham Hotspur of late, and when pushed as to whether he will form part of his pre-season plans the response was telling.
"I don't know. I don't expect this [situation]. If yes [he is still here in pre-season], I need to think about it," he told reporters. "I will have to talk about the situation but I expect an answer soon after the weekend and not another 10 days.
"If you offer a player a new contract and a good contract that means you like to keep the player. I don't need to explain more because if we don't want the player to stay longer we don't offer a new contract."
Barkley has five goals and eight assists in 35 appearances in the Premier League this season, while also netting in one of his three cup outings.