Monica Lewinsky has a tentative immunity deal to cooperate with Kenneth Starr's investigation of an alleged presidential affair and cover-up, legal sources said Tuesday.

Lewinsky's lawyers, Jacob Stein and Plato Cacheris, reached the agreement Tuesday morning at a meeting in Starr's office, said the sources, speaking on condition of anonymity.The agreement for Lewinsky's testimony that she had sexual relations with President Clinton was reached after the former White House intern was interviewed for five hours Monday by Starr's prosecutors in New York City.

Lewinsky's account also included information relevant to Starr's probe of possible obstruction of justice by Clinton and his associates in Paula Jones' sexual harassment case against the president, said the sources.

Lewinsky's lawyers scheduled a news conference for Tuesday afternoon.

Her account closely tracked her lawyers' proffer of evidence to prosecutors early in the probe, according to a key source. In that proffer, Lewinsky was said to have told of having a sexual relationship with the president. She did not say Clinton asked her to lie, the sources said.

The source said the earlier proffer contained "a fair amount of information" dealing with Lewinsky's conversations with the president and his con-fi-dants about how they would deal with the Paula Jones sexual harassment lawsuit against Clinton. The president denied under oath in the Jones case that he'd had sexual relations with Le-win-sky, and she filed an affidavit in the suit saying "I have never had a sexual relationship with the president."

Lewinsky's former friend, Linda Tripp, whose secret tape recordings triggered the criminal investigation of the president, returned for more testimony before the grand jury Tuesday.

"It's going to be an interesting week, we think," said Tripp's spokesman, Philip Coughter, who accompanied her to the federal courthouse. A number of Secret Service personnel also entered the courthouse to testify before the grand jury in the perjury and obstruction probe.

Six additional Secret Service uniformed officers have been subpoenaed to testify this week, Mike Leibig, head of an association of Secret Service officers, said Monday night. Leibig said 11 Secret Service personnel have given grand jury testimony in the probe.

The Lewinsky-prosecutor talks came on a day that Starr won a majority victory from a panel of the U.S. Court of Appeals for the District of Columbia.

In a 2-1 decision, the panel rejected Clinton's claim of attorney-client confidentiality and ordered presidential adviser Bruce Lindsey to answer questions before a grand jury.

The panel majority said none of Lindsey's conversations as a White House adviser were protected from grand jury testimony. But the judges said Lindsey - as a deputy counsel - dispensed legal advice in "at least one" conversation, thus permitting a ruling on whether government lawyers could withhold information in a criminal investigation. The answer was no, the majority said.

A meeting with Starr's investigators has been a requirement for Lewinsky's immunity since prosecutors first confronted her Jan. 16 with 20 hours of secret tape-recordings on which she alleged to Tripp an 18-month presidential affair and cover-up.

Deputy Whitewater prosecutor Robert Bittman and Starr's ethics counselor, Sam Dash, participated in the questioning, along with a female colleague, the sources said.

"It wasn't a cross-examination; they weren't trying to browbeat her; they were just trying to get some answers," said one source.

It was not clear how Monday's talks would affect Clinton's legal strategy. His lawyer, David Kendall, apparently was still trying to reach a compromise with Starr over the subpoena.