Officials in the U.S. attorney's office, stung by a public defender's use in court of a prosecutor's confidential letter to colleagues, are considering curtailing future meetings with public defenders, according to informed sources.

Under a proposal being considered by U.S. Attorney Stanley S. Harris, prosecutors would no longer meet informally with attorneys from the Public Defender Service in certain cases and in those cases would conduct pretrial negotiations only in writing, these sources said.

Authorities in the D.C. Public Defender Service, citing the proposal--one of several reportedly being considered by Harris--as the result of a widening rift between the two agencies, said the restrictions could threaten defendants' rights to a fair trial and would further clog an already overloaded court system.

Federal officials said the restrictions being considered would not directly affect defendants and argued that they may now be necessary to guard the confidentiality of informal meetings.

The disagreement was precipitated by an incident earlier this month in which public defender James McComas introduced in D.C. Superior Court a memorandum to colleagues from Assistant U.S. Attorney Cary M. Feldman.

In the memo, written shortly after a jury found defendant Ondrea Gant guilty of raping a 12-year-old, Feldman accused the judge presiding over the case of "conspiring to rob" Feldman of his credibility with the jury and labeled McComas "the most treacherous, unscrupulous advocate I've ever seen."

McComas' supervisors in the Public Defender Service, who declined to say how the memo was obtained, said McComas was duty-bound to introduce it in court as evidence that Feldman had waged a vindictive campaign to convict Gant.

Top officials in the U.S. attorney's office, saying Feldman had exercised "bad judgment" by putting his personal feelings in writing but had a right to "blow off steam" among colleagues, then learned that McComas' use of the memo had been approved by his supervisors, including PDS director Frank Carter.

The Public Defender Service, a city agency, defends more than 1,000 criminal cases a year, including between 60 percent and 70 percent of the city's homicides. Prosecutors in the U.S. attorney's office represent the government in those cases.

Attorneys from both agencies traditionally meet informally before trials to discuss evidence and possible plea bargains. In a March 11 letter concerning the defendant in a murder case, Assistant U.S. Attorney William D. Nussbaum told McComas--who is the defendant's attorney--that he would not meet personally to discuss evidence.

Nussbaum, whose letter Harris approved, told McComas it was necessary to proceed in writing to "minimize the chance of misunderstandings between us."

Federal officials said Nussbaum's action is based a 1977 D.C. Court of Appeals ruling that it is sometimes "highly desirable" to conduct pretrial negotiations in writing. PDS officials said such letters are not unusual, but that they have always followed informal discussions.

Last week McComas wrote the judge in the case, George H. Revercomb, complaining about Nussbaum's behavior and asking for an off-the-record meeting with Revercomb to discuss the matter. Revercomb refused.

PDS officials said prosecutors also have refused to discuss the issue. Said one federal law enforcement official, explaining the hard-line stance: "This is not an issue that we want to talk about."