White House and top agency officials have undercut the effectiveness of federal ethics laws in recent years by failing to put a high priority on their enforcement, Common Cause said in a report issued today.

The self-described citizens' lobby said a survey of 50 officials designated by federal agencies as "ethics officers" found that only a few spend more than 15 percent of their time on ethics-related matters.

Common Cause also said most ethics officers make decisions about potential financial conflicts of interest ad hoc rather than systematically, frequently do a poor job of educating employes about potential ethical problems and rarely exchange information with criminal investigators about possible wrongdoing.

The group said many ethics officers delegate responsibility for managing programs to subordinates, but "it is nonetheless striking that so many of them devote so little time to these duties."

"The areas of concern we have identified appear to flow from insufficient commitment from high-level officials, both in the White House and in the agencies," Common Cause concluded. "This results in low visibility for many ethics programs, which hinders their effectiveness."

Common Cause President Fred Wertheimer also said he had asked Congress to explain how it reviews the disclosure forms that its members must file about their personal finances.

Wertheimer said his letters to the Senate Select Committee on Ethics and the House Committee on Standards of Official Conduct were prompted by "recent events that raised serious questions" about the thoroughness of the committees' examinations -- an apparent reference to the completeness of financial information that Rep. Geraldine A. Ferraro (D-N.Y.) filed in the years before she ran as the Democratic vice-presidential nominee.

Common Cause noted that a number of regulations and laws were written in the wake of the Watergate scandals to hold federal employes to certain standards of conduct. But, it said, "instances of improper conduct have continued to mar every recent administration."

"The present administration has had particular problems in this regard," the group said, citing several high-ranking Reagan administration officials who resigned or were embarrassed after becoming entangled in ethics problems.

David H. Martin, director of the Office of Government Ethics, said yesterday he agreed with some of Common Cause's criticisms, but said his office has worked hard to train agency ethics officers.

After Reagan appointed him in July 1983, Martin said, his office launched an aggressive training program that has won praise from Congress.

One key problem with the current system, Common Cause said, is that most agency ethics officers, who are responsible for advising employes and monitoring compliance with federal laws, generally are general counsels who are busy with other matters.

Among the most frequently ignored regulations, the Common Cause study said, are post-employment rules, which limit contact between an employe and the agency where he worked. According to the group's survey, eight agencies, including the Commerce Department, said they never "monitor compliance" with such rules. Another 15 agencies said they do not keep records of noncompliance situations for reference when similar problems arise.