WASHINGTON (AP) _ Usually antagonists, Whitewater prosecutor Kenneth Starr and the Clinton Justice Department have joined forces to appeal a judge's ruling on alleged grand jury leaks during the Monica Lewinsky investigation, legal sources say.

Starr asked an appeals panel in mid-July to intervene quickly and overturn the findings of U.S. District Judge Norma Holloway Johnson, said the sources, who spoke on condition of anonymity.

The Justice Department has had its own inquiries into leaks that may have come from Starr's office. But it has joined the independent counsel in his appeal, the sources said.

At issue is whether the independent counsel improperly leaked secret grand jury information to the news media. Federal rules prohibit prosecutors and court officials from disclosing evidence brought before a grand jury.

The Justice Department is not accused of leaking in this case, but the department may be worried that the court is setting an unreasonable precedent. Justice officials have explained in the past that if they got involved in the case it would be to ensure that their own prosecutors are not hamstrung in giving reporters information in the future.

Though the impeachment investigation is long over, the judge's investigation into alleged leaks remains a concern for the embattled independent counsel's office. The prosecutors want to clear their names and avoid possible penalties, including fines or action against their law licenses.

In his appeal, which remains under seal, Starr argues that Johnson was wrong in ruling that investigative matters not yet brought before a grand jury should be covered by secrecy rules that apply to the grand jury itself.

Starr also challenged the standard Johnson used to determine there was preliminary evidence to believe that news articles in question likely came from Starr's office, the sources said.

The sources include lawyers or employees inside the federal courthouse in Washington. They are not members of Starr's office or President Clinton's legal team, which filed the original complaint in spring 1998 accusing Starr's office of illegal leaks.

Starr asked the appeals court to intervene on an expedited basis after Johnson ruled in the leaks case, the sources said. They weren't more specific except to say the ruling involved a Feb. 1 complaint filed by presidential lawyer David Kendall that alleged additional grand jury leaks by Starr's office.

The leak accusations were used by Clinton's defenders to undermine the credibility of Starr's investigation, especially during the sensitive months surrounding the president's impeachment and acquittal.

Most of the leaks investigation has been played out in secret, although documents unsealed by courts give the public a taste of how vigorously both sides have waged battle.

Kendall touched off the court fight during the early days of the Lewinsky investigation, when he accused Starr's office of illegally leaking damaging information about the president, including the testimony of Oval Office secretary Betty Currie.

Kendall cited numerous newspaper and TV reports quoting anonymous sources as describing evidence that prosecutors were bringing before the grand jury.

Johnson, who as the chief judge of the federal court in Washington oversees grand jury investigation, ruled last summer that there was preliminary evidence suggesting Starr's office made ``serious and repetitive'' violations of grand jury secrecy rules.

The judge cited 24 news stories she said likely came from Starr's office. They included general accounts of Starr's ``next moves'' and specific reports that the prosecutor had rejected a proposed immunity deal for Ms. Lewinsky.

The judge ordered a court official, called a special master, to investigate further.

Johnson also concluded that, at least in the court district covering Washington, it has been clear that ``government attorneys may not reveal documentary evidence that is likely to be presented to the grand jury'' _ even if it was not yet presented.

Even before his appeal, Starr has made clear he disagreed that information not yet presented is covered by secrecy rules.

``It's definitely not grand jury information, if you are talking about what witnesses tell FBI agents or us before they testify,'' he said last summer.

Starr also has argued that White House and defense lawyers _ not the prosecutor's office _ were the prime suspects for the leaks. Kendall has countered that the White House had no interest in leaking information damaging to the president.