D.C. Police Chief Maurice T. Turner Jr., reacting angrily to a report that the FBI is investigating allegations of police corruption, defended his department yesterday and vowed that "no blue veil" shields "wrongdoers within our own ranks."

At a news conference at police headquarters attended by virtually all of the department's ranking officials, Turner refused to answer any questions, instead reading in clipped tones from a three-page prepared statement that cited the department's "vigorous investigations of police transgressions."

The Washington Post reported yesterday that sources said the FBI is probing an alleged pattern of police officers profiting from their handling of drug trafficking cases. Allegations also have been made that internal police department investigations of such misconduct have been covered up, sources said.

Turner yesterday criticized The Post for publishing a story that he described as "unsubstantiated."

"When vague allegations of corruption are lodged by sources that are nameless, faceless and blameless, the very character of this department is defamed," he said. "I am left wondering about the motivation of The Washington Post to publish such an unsubstantiated article which generates suspicion and distrust of all Metropolitan Police Department law enforcement personnel."

Post Managing Editor Leonard Downie Jr. responded, saying, "The story is correct."

The investigation of alleged police corruption is a new element in a wide-ranging series of probes of the D.C. government, including inquiries into city contracting, possible obstruction of justice by associates of Mayor Marion Barry and expenditures from accounts controlled by the office of the mayor.

Barry and Turner said Wednesday they were not aware of an FBI investigation of alleged police corruption and, while acknowledging the possibility of isolated individual wrongdoing, denied that there is a pattern of impropriety in the 3,880-member department.

In an interview yesterday, Barry said that a senior Justice Department official had assured his staff that there is no widespread federal probe of police corruption. He refused to name the official, describing the official as "very high" but not Attorney General Edwin Meese III. "That senior official assured my staff that it was a preliminary discussion with several police officers -- no widespread probe and that they were upset with the story," Barry said.

Justice Department officials said last night that they could not confirm or deny that such a conversation took place. Spokesmen for the U.S. attorney's office and the FBI declined to comment on the probe.

Turner sought to boost morale on a day when many ranking police officials expressed shock and anger at reports of the probe. Just before stepping down from the platform, the police chief declared, "I called this press conference for your help to get this message out to the community: I am upset and pissed off."

Turner did not address specific areas of the probe, including allegations that FBI agents have questioned several District police officers who have said that other officers have kept money and drugs confiscated in drug raids and falsified reports by listing only part of what was seized.

He dismissed allegations that the department's Internal Affairs Division -- the in-house unit that investigates allegations of wrongdoing among police and city officials -- covered up such alleged misconduct.

"We are noted for our fair and vigorous investigations of police transgressions and no blue veil of protection exists that would shield wrongdoers within our own ranks from accountability," Turner said.

Police officers who behave improperly are severely disciplined and, in some cases, have faced criminal charges as a result of internal investigations, Turner said.

Pointing to an internal drug use screening program he initiated in 1982, Turner said that since 1984 investigations have been conducted of 33 officers who tested positive for drugs, and 21 of those were fired.

A special police panel appointed by Turner this month is investigating whether police officials, including members of the Internal Affairs Division, tampered with drug testing procedures in at least one case in which a high-ranking official's urine tested positive for drugs.

The panel also is investigating other "irregularities" in the drug screening programs and "allegations of misconduct and possible criminal violations," including bribery, tampering with physical evidence and standards of conduct, according to letters sent by police union officials to Barry and to U.S. Atttorney Joseph E. diGenova.

There is no indication that the allegations of tampering with drug test procedures are related to the FBI probe of the department.

"We stand ready to investigate any allegation of wrongdoing which is brought to our attention," Turner said. "And if there are a few among us who have chosen to violate the public's trust, they will learn the harsh reality that those who enforce the law are not above it."

Since the disclosure of the undercover phase of the contracting probe in May, Barry and other city officials have publicly challenged federal prosecutors to present sufficient evidence for indictments and have characterized the investigation as racially motivated.

"I recall the times in law enforcement that when an announcement of illegal activity was made it included the arrest or the indictment of the accused," Turner said yesterday. "I fear at this point that these allegations have only served to jeopardize departmental efficiency, depress morale, undermine public confidence and destroy interagency trust and cooperation."