PHILADELPHIA (AP) _ A Philadelphia police commander once considered a leading candidate for commissioner was among five ex-officers charged in the latest indictment returned in the FBI's three-year police corruption investigation.

A federal grand jury charged Thursday that former Chief Inspector Eugene Sullivan, 63, presided over an extortion ring that collected $15,000 a month shaking down brothels, numbers writers and video-poker machine owners.

The indictment brought to 34 the number of officers charged with extortion in the inquiry, which ''has not slowed down,'' said U.S. Attorney Edward S.G. Dennis Jr.

Twenty-four officers have pleaded guilty or have been convicted, including former Deputy Commissioner James Martin and Chief Inspector Joseph DePeri, who were jailed. Three were acquitted and seven, including those identified Thursday, are awaiting trial.

Sullivan was dismissed in November after he was implicated by a former vice officer in trial testimony. Sullivan, considered for the top police job in 1979 under the administration of Mayor William Green, had said he was being made a scapegoat by former vice-squad officers dealing for leniency.

''Sullivan had people working for him who collected money and passed it up through lieutenants to him,'' Dennis said Thursday in announcing the indictment.

Indicted with Sullivan, the second-highest police official implicated in the inquiry, were former lieutenants Walter McDermott, 48, and John Czmar, 39, and former vice patrolmen Robert ''Moe'' Schwartz, 42, and William Maahs, 40.

''The five defendants are charged with participating in an extortion scheme which netted, at its peak, $15,000 per month in illegal protection payoffs from vice operations,'' Dennis said.

The extortion allegedly took place between 1978 and 1984, the grand jury charged.

Named as co-conspirators but not indicted were six other former officers. Three of them have been found guilty in previous trials; two have never been charged and one is deceased.

Sullivan, charged with 30 counts of extortion and conspiracy, commanded the Northeast Police Division from 1980 to 1984. He faces the stiffest penalty if convicted - 600 years in prison and a $300,000 fine.

Martin, who continued to take payoffs after being named the No. 2 officer in the department following the election of Mayor W. Wilson Goode, was sentenced to 18 years in jail. DePeri got 15 years.

If convicted, McDermott could faces a sentence of as much as 380 years; Schwartz, 160 years; and Czmar and Maahs 40 years each.