Atlanta civil rights activist Hosea Williams charged yesterday that a federal probe of D.C. Mayor Marion Barry and District contracting is part of a nationwide effort by the Reagan administration to topple black elected officials.

"There is unquestionably an effort to destroy and defame black leadership in this country," Williams said at a Blacks in Government conference at the Washington Hilton. " . . . There was a failure by the white power structure to co-opt them. Blacks did not capitulate, and now there's an effort to destroy them."

Williams, an Atlanta City Council member and a longtime leader of the Southern Christian Leadership Conference, said federal probes of Barry's administration and of drug allegations against former state legislator Julian Bond and other prominent blacks in Atlanta are part of a pattern of racially inspired, broad-brush criminal investigations across the country.

"It comes from {a} signal that the Reagan administration is showing," he said.

Barry and his top aides earlier this year criticized a wide-ranging federal probe of D.C. government contracting, accusing U.S. Attorney Joseph E. diGenova of abusing the grand jury subpoena process.

Barry also accused federal prosecutors of trying to "run me out of office" by planting leaks in the news media about allegations that he had used cocaine and maintained a sexual relationship with convicted drug dealer Karen K. Johnson.

The mayor filed suit against diGenova, alleging misconduct and seeking to stop future leaks, but the case was dismissed July 24 by Chief U.S. District Judge Aubrey E. Robinson Jr. Robinson ruled that none of the newspaper articles and TV broadcasts on which Barry based his case showed leaks of secret grand jury information or misconduct by diGenova.

DiGenova's office said the judge's ruling "speaks eloquently for itself" and that diGenova would have no further comment.

Williams, speaking at a news conference called to discuss problems with the enforcement of federal equal employment opportunity laws, linked the investigations in Washington and Atlanta to those of black officials in Chicago; Memphis; Gary, Ind., and Tuskegee, Ala.

"I see a pattern across the country and I think there's a definite effort to defame black leadership," he said.

However, Williams, a one-time aide to the Rev. Martin Luther King Jr., conceded that some black leaders have "fallen into the trap of trying to mimic {corrupt behavior} of their predecessors."

"Not only are black leaders not able to get away with doing identical to that which their white predecessors did, but black leaders' hands must be clean," he said. " . . . I'm saying if a black leader is wrong, that black leader should be convicted and punished, but don't indict the black community."

Rubye S. Fields, president of the 20,000-member Blacks in Government, and Oscar Eason Jr., the group's board chairman, last week blasted the performance of the Equal Employment Opportunity Commission and called for creation of a separate agency to handle discrimination complaints of federal workers.

EEOC offices, which handle the final stages of discrimination cases in the federal bureaucracy, are underfunded, understaffed and "typically relegated to a lower status in an agency," according to a 20-month study by the Washington Council of Lawyers.

"The process of discrimination complaints must be taken out of the hands of government agencies and placed with a separate, independent agency," Williams said yesterday. "Putting the fox in charge of the chicken house defies all logic and common sense."

Eason, citing numerous setbacks in equal employment and civil rights efforts during the Reagan administration, told reporters: "Racism is on the rise in this country and we simply have to do something about it. The work place is merely a mirror reflection of what's going on out there."

Blacks in Government, a group founded 10 years ago to promote the interests of black government employes, is conducting a five-day training conference that concludes today.