Jonas Gutierrez is concerned that the club will offload their star players and stall any progress the club is making. And Gutierrez has called on the club to tie down key performers such as Jose Enrique and Fabio Coloccini.
He said: "It is really important that [Enrique and Coloccini] stay.
"They are my best friends but they are also very important players. We are all part of a group, and it is important that group stays together.
"Sometimes, things happen that mean it is very difficult for a player to stay. Look at Andy in January - £35m, Liverpool, that is difficult for the club and the player to turn down. That is football.
"But in general, I want all of the players at this club to stay. That will make it much easier for the team to be strong next season."
Newcastle are currently ninth in the Premier League with 35 points, and Gutierrez admits he has been delighted with their progress this term following promotion last season.
"At the start of the season, if someone had said we would finish in the middle of the table, we would have taken that," he said.
"Last year we were in the Championship, so it was always going to be a tough season back in the Premier League - there are a lot of strong teams to play against.
"The middle of the table was always going to be good for us, but now we are in the middle of the table, we need to keep pushing up."
