Dr. Dirk J. Struik yesterday bitterly criticized Middlesex County District Attorney George E. Thompson for the long delay in his trial.

Struik, suspended M.I.T. professor, is presently under indictment charging him with advocating the overthrow of the government by force or violence.

In a letter to his "hundreds of friends and supporters," the M.I.T. professor demanded a decision "one way or the other. I dislike thoroughly being suspended in mid-air."

Terming the delay a "refined cruelty" on the part of the District Attorney, Struik complained that "it will be some time before the public can know whether or not a man may hold and express a point of view unpopular in some high places without going to jail."

Thompson: "No Comment"

Thompson declined to comment yesterday on Struik's statements.

The M.I.T. professor was indicted by a Middlesex County Grand Jury in September, 1951, with Harry E. Winner, a Greater Boston businessman, and Mrs. Margaret Gilbert, a Cambridge resident. Mrs. Gilbert is fighting extradition from Illinois on an appeal to the Superior Court of that state.

Thompson, in a statement earlier this month, declared that he wished to proceed against all three defendants at the same time and would wait until Mrs. Gilbert's extradition case was decided.