Federal prosecutors said yesterday that defense lawyers for John W. Hinckley Jr., who is accused of the attempted assassination of President Reagan, should not have access to notes made by government psychiatrists about Hinckley because their examinations have not been completed.

In papers filed in U.S. District Court, prosecutors said they have been told by these psychiatrists that such premature disclosure to the defense would be "extremely harmful" to their work because of the risk that Hinckley himself could adjust his responses if he knew what the doctors' reactions have been.

The prosecution added that none of the notes or other records made by those psychiatrists have even been disclosed to the government.

Hinckley's defense lawyers argue that they need that information to help them decide whether to contend that Hinckley was insane at the time of the shooting last March 30. Hinckley is accused of attempting to kill Reagan and of shooting three other people outside the Washington Hilton.

The government contends that if the defense notifies the court that it will raise an insanity defense, the doctors' complete report will be turned over. If government doctors conclude there is evidence of insanity, that information will be turned over to the defense in any case.