Karanka was in a joking mood when he was asked about Gibson's England chances, saying when asked what he would say to Sam Allardyce: "Everything - that he's a bad player, a bad person..."
He continued in a more serious tone, adding: "He is the kind of player that just looking at him, you can feel that he is a really good lad.
"He's a player who likes and who wants to improve every single day and for that reason he has improved in the last two-and-a-half years.
"He has played the last five games in the Premier League and he has shown his experience. But he has to continue to improve because, for me, he is an important player on the pitch if he plays in the way that he is playing.
"He's a good character, but sometimes you can drive yourself crazy. If one day he goes to the national team, it would be amazing for him and it would be amazing for the club because he has grown up here and he's part of this club. It would be fantastic.
"But at the moment he is playing here and he has to think that we have to win the games here and then he can think about the national team.
"But again, that moment hasn't happened, so I prefer to think that the is going to play amazingly against Tottenham, then he is going to play amazingly against West Ham and then what happens is not my problem."