Union leaders representing Harvard security guards reached an agreement with University negotiators last Tuesday on the assignment of overtime hours, the union president said yesterday.

The parties failed to settle the major question of whether guards should work in only one area of the University or anywhere on campus, Robert V. Travers, president of the Harvard University Employee Relations Association (HUERA), said. The issue of flexibility is "the only thing holding the contract up," he added.

The HUERA lawyer is drafting a compromise proposal on this issue to present to University negotiators tomorrow, he said.

Capt. George L. Walsh, security coordinator for the Harvard Police, said Tuesday, the police feel a guard should be able to work anywhere in the University and that "there should not be specialized guards."

The new overtime agreement stipulated that a list of all overtime openings be posted and that records of who has worked overtime be available to all guards. These steps are designed to alter the current situation where just a few guards get to work overtime, Travers said.

"Constructive Session"

Edward W. Powers, director of employee relations, who represented the University in the meeting, yesterday characterized the session "constructive."

The next step should be a series of meetings between Travers and the police, but no date has been determined, he added.

The guards have continued to work during the negotiations although their last contact expired Nov. 30, 1975. However Harvard Police officials said yesterday they consider the new unsigned contract in effect.