The Fraternal Order of Police last night charged that D.C. police officials concealed crucial findings in their probe of the department's drug-testing program, and called on Mayor Marion Barry to initiate an independent investigation of the department's conduct.

In a 75-to-0 vote, union members said Barry should investigate the department's drug-screening program, which had been accused of favoritism and tampering with physical evidence. They also called for a review of a police panel's recent investigation of the controversial program, and demanded that Police Chief Maurice T. Turner Jr. release all records of the department's investigation.

Friday night, Turner said in a prepared statement that the panel investigating the drug-screening system found no basis for allegations raised last summer by two drug screening operators.

Turner reprimanded two police officials, Assistant Chief Carl Profater and Deputy Chief Jimmy Wilson, for "errant judgment" and making false statements to the investigative panel. He also reprimanded Capt. Robert J. Noyes, a former drug-screening official, for violating department rules governing the anonymity of the tests.

Gary Hankins, chairman of the Fraternal Order of Police, said after the union vote that the report Turner released last week was "severely edited" to hide evidence. Revelations within the department's unedited report, he said, show violations that merit more disciplinary action than Turner's reprimands. "In this case, I really believe the chief has let personal loyalty to friends overcome his responsibility to the department and the community," he said.

Capt. William White III, a police department spokesman, declined to comment on the union's allegations.

In what he called a "calculated effort" to conceal its findings, Hankins said a 17-page report was described as a complete summary of the investigation when it was released last week. But he said the department actually prepared a 50-page report that more vividly characterizes the extent of impropriety by police officials associated with the drug-screening program.

"The documents released last week were only a fraction of what was found out in the investigation," Hankins said. "We think the timing and nature of documents released was intentionally done . . . in the hope that everything would just blow over. They seem to have made a calculated effort to minimize what they {the reprimanded officers} were doing."

Hankins said he and union steward Ron Robinson met with Turner yesterday afternoon to discuss the investigation, and said Turner sent him the 50-page report a few hours after the meeting.

In the 17-page summary, an in-house panel of D.C. police officials found no merit to allegations of improprieties and possible criminal violations in the department's drug-testing program.

But the panel members cited "several instances of negligence, oversight, deviations from procedures and poor judgment." They said Profater and Wilson had made false statements to the panel and "contributed to the perception that there are improprieties and favoritism in the department's drug-screening process."

The probe was triggered when two drug-screening workers, Marguerite Anastasi and Vernon Richardson, sent letters to Barry and U.S. Attorney Joseph diGenova that accused D.C. police officials of tampering with physical evidence, violations of standards of conduct, and other improprieties.

The letters described a May 30, 1985, incident in which a lieutenant seeking promotion to captain was given an unprecedented second test after his first sample was found to be tainted with marijuana. The samples, which are not supposed to leave the clinic except for confirmation tests, were taken to a laboratory in North Carolina. No marijuana was found in the second sample or confirmed in the first, and the lieutenant received his promotion on June 7, 1985.

Profater and Wilson are both longtime members of Turner's inner circle as well as close friends. Letters of reprimand are the strictest form of discipline short of sending an officer before a police trial board for possible termination, fines or suspension.

Reprimands against high-ranking officials are rare and are considered a possible impediment to advancement.