A federal judge, faced with a jury deadlocked for nearly 35 hours, dismissed charges today against seven police offers in the 1969 slaying of two Black Panthers in a predawn raid.

Senior U.S. District Court Judge Joseph Sam Perry issued his decision when the jury, which began deliberations Friday morning, declared itself deadlocked following a 318-day civil trial, the longest in federal court history.

Proceedings in the $47.7 million civil rights trial covered an 18-month period, beginning on Jan. 5, 1976.

The plaintiffs "have failed to sustain a version of proof in every claim," the 80-year old judge told a courtroom packed with about 120 people in announcing his decision to grant a defense motion for dismissal.

Attorneys for the plaintiffs -- the families of Panther leaders red Hampton and Mark Clark -- said immediately they would appeal.

Jeffrey H. Haas, 34, one of two attorneys for the plaintiffs, said he was "absolutely stunned" by the decision.

"It's clear he (Perry) is part of the cover-up of the murders of Fred Hampton and Mark Clark," Haas said. "I think the people will be outraged by this. We saw $2 million of city and county money and millions in federal money spent to continue the cover-up."

The defendants were among a police task force, authorized by the state's attorney, that burst into a Panther headquarters on Dec. 4, 1969. Authorities at first maintained they engaged in a gun battle with the Panthers. Later investigation indicated that only one shot was fired by a -- by Clark -- and 99 were fired by police. The defense maintained the Panthers fired 15 shots.

At issue in the case was whether the seven officers deliberately shot Illinois Panther Chairman Hampton, of Maywood, III., and Clark, a deputy from Peoria, III. Four other persons were wounded in what was described as a raid in search of illegal weapons.

Defendants originally included former Cook County State's Attorney Edward V. Hanrahan, whose investigators participated in the raid, and 20 other federal and local law enforcement agents. Those charges were dismissed last april. Only the seven policemen who actually fired shots in the raid were defendants at the end of the trial.

Families of Hampton, Clark and the seven survivors filed the lawsuit in 1970, charging the victims' civil rights were violated. The defendants also were charged with wrongful death and using excessive force.

Attorneys representing the Panthers, G. Flint Taylor Jr., 31, and Haas, repeatedly attacked Perry during the trial as biased and hostile.

Haas said, "whether it's his (Perry's) will or his whim, the 18 months have been excruciating. The law has been turned upside down and stretched every which way to defeat us. We can't underestimate the vengeful side of Judge Perry. . . ."

A U.S. marshal said that the jurors did not wish to speak to reporters, but Taylor said two jurors approached him after the verdict and said they were shocked by Perry's action.

The jurors were sequestered Thursday after closing arguments ended amid a shouting match between attorneys.