A federal grand jury that has been investigating drug trafficking here, which purportedly involves local residents and athletes at the University of Virginia, indicted 11 persons today on charges ranging from tax evasion to racketeering.

The indictments were sealed, and no names were revealed.

Prosecutors declined to comment until a news conference scheduled for Thursday morning, when they are expected to name those charged.

Alexandria lawyer Marvin D. Miller, who represents Trevis Lynch Poole, whose arrest last summer prompted the wide-ranging investigation, said today he expects his client to be indicted on charges of running a continuing criminal enterprise.

The Daily Progress, a local newspaper, said that the prosecutors plan to charge as many as 13 others in criminal informations, a process that does not require grand jury action. Informations are usually filed when a defendant has agreed to plead guilty.

Both the Charlottesville chief of police and the university's athletic director have said they expect some athletes to be indicted.

Four current or former Virginia football players have been questioned in connection with the investigation. One of them, Kevin Turner, who made the team without first winning an athletic scholarship, has been convicted of two counts of distributing cocaine in federal court and is awaiting sentencing.

The other players questioned, according to the Roanoke Times & World News, were former tailback and 1985 Atlantic Coast Conference player of the year Barry Word, former place kicker Kenny Stadlin and starting tailback Howard Petty.

The Progress reported today that several current and former athletes were believed to have waived their right to be indicted by the grand jury and would be among those charged in the informations.

The grand jury has been sitting since Nov. 1, but it was only after the cocaine-induced death of Len Bias, the University of Maryland basketball star, that the inquiry gained wide attention.

There has been speculation that some prominent Charlottesville citizens, as well as the athletes, would be charged. Charlottesville Police Lt. James Haden said he believes "some people not even thought of as being drug dealers" may be charged.

Today's indictments were described only as being against six men and five women, identified in public only as John and Jane Doe. Prosecutors said they were indicted on seven felonies.

The count that Miller said will be placed against his client, running a continuing criminal enterprise, is a violation of a racketeering statute. It carries a minimum prison term of 10 years without chance of parole and a possible fine of $250,000.

To win a conviction, prosecutors must prove the defendant supervised five or more people in a criminal enterprise that yielded him substantial revenue.

Miller said his client, whose Fluvanna County farm was raided by police on July 4, 1985, would plead not guilty to that charge. Poole has pleaded guilty to a cocaine distribution charge after police said they found 3 1/2 pounds of the drug at his home.

He is "an unsophisticated kid, and they're trying to make him out as Attila the Hun," Miller said. He criticized prosecutors for their "ballyhoo" over the investigation.

The other charges returned by the grand jury today include distribution of a controlled substance, or possession with intent to distribute; use of communications facilities in connection with a felony; conspiracy; use of interstate commerce and foreign travel for racketeering purposes; aiding and abetting a crime, and tax evasion.

The tax evasion charge carries a potential five-year prison term and $250,000 fine, according to law enforcement officials. The other charges carry potential 15-year terms and $250,000 fines.

A special task force, which presented information to the jury, has concentrated on distributors, not small users, according to law enforcement officials. The task force's 11 members include representatives of Charlottesville, Albemarle County, state and university police; the FBI, and the Internal Revenue Service.

In addition to Turner, the other university student who pleaded guilty to cocaine distribution charges was Ruben Dario Vahos, a Virginia law school student. He was denied his law school diploma after his conviction. Both he and Turner are to be sentenced Monday.

The University of Virginia athletic program began a mandatory drug testing program in December, a program that Virginia Athletic Director Dick Schultz has said was not related to task force or grand jury activity. He also said that any university athlete who is indicted or charged in the drug probe would be suspended from varsity athletics.