President Clinton is invoking executive privilege to shield top aides from testifying about internal White House discussions on the Monica Lewinsky investigation, according to lawyers involved in the case.

White House lawyers spent the weekend preparing legal briefs to assert executive privilege on behalf of the president before a federal judge at a hearing that could occur as early as this week.The president decided to take the step, which has profound legal and political implications, after prosecutors last week filed a motion to compel testimony from Bruce Lindsey, the president's closest friend and adviser at the White House.

Lindsey, who appeared before the federal grand jury for two days last week, declined to answer a number of questions from the independent counsel investigating the Lewinsky matter, citing the confidentiality of discussions between the president and his senior advisers.

The matters the White House deemed covered by executive privilege included discussions between the president and his aides on how to respond to prosecutors' and reporters' inquiries on the nature of the relationship between the Clinton and Lewinsky, according to a White House official.

The White House and Clinton's private lawyers are preparing a long brief, asserting that the matters the independent counsel, Kenneth Starr, is seeking to question Lindsey about are covered by executive privilege.

White House officials on Tuesday night declined to discuss the brewing dispute over the assertion of privilege, saying they will respect a judge's demand that the matter be argued in private.

But the legal maneuvering presages a lengthy legal battle over the issue of whether the murky doctrine of executive privilege extends to internal White House deliberations over matters under criminal investigation.