In addition they have also released three youth players - Scott Anson, Paul McInnes and Thomas Nolan.
A statement released on the club's website however, revealed that the club have no plans to reduce Jim Jefferies' budget for the first-team squad.
"Jim Jefferies has been informed that there are currently no plans to reduce the first team squad budget next season, which has been increased in each of the previous three seasons to its current level of circa £2 million.
"The club wishes to extend its thanks and best wishes to "out of contract" players Allan Johnston, David Lilley and Grant Murray who have been great servants to the club over a period of several years and have always displayed a highly professional approach to their training and playing duties.
"Club Captain Gary Locke is also out of contract but has been offered a coaching role with a view to retaining the benefit of his extensive experience. He is considering his options at present.
"Scott Anson, Paul McInnes and Thomas Nolan joined the first team squad last season having graduated from the club's youth development scheme.
"As part of the planned reduction in the size of the first team squad, they have not been offered new contracts but that should not detract from the undoubted potential which they all possess.
"Everyone at the club who has observed their progress is confident that they will soon find new clubs and continue to play professional football at a high level for many years to come."