The U.S. Justice Department has obtained committments from officials in the Soviet Union and Israel to make available documentation and whitnesses that can be urged in deportation proceedings against suspected Nazi war criminals who have obtained American citizenship.

In operation only seven months, the Justice Department's Office of Special Investigations has begun a race against time to close the files on about 250 potential war crimes cases before the majority of the suspects and witnesses are either dead or too old to testify, Walter Rockler, director of the U.S. effort, said in an interview this week.

The aim of the project is to deport Nazi war criminals who fraudulently obtained U.S. citizenship by covering up their past when they immigrated. Most of those targeted for expulsion are former guards in prison camps in Germany and Eastern Europe, or German SS troops who participated in mass executions during the Nazi drive into the Soviet Union.

While the trail is getting cold on many of the suspects, Rockler acknowledged, the U.S. government has finally -- more than three decades after the close of the war -- launched a major effort to deny war criminals a sanctuary in America.

"It's inappropriate to have a bunch of murderers wandering around the United States and passing themselves off as decent citizens," Rockler said. Rockler, who was a war crimes prosecutor during the Nuremberg trials from 1947 to 1949, is here to solicit cooperation from the Israeli government. f

In two months, Rockler will leave his temporary U.S. post and return to his private law practice. He is expected to be succeeded by Allan A. Ryan Jr., his deputy, who accompanied Rockler on his visit here and to Moscow.

Rockler and Ryan said a major breakthrough during their Moscow trip was a pledge by high-level Soviet government attorneys to permit any war crime witnesses "able and willing to travel" to go to the United States to testify in a trial.

The Soviet officials also promised to allow Justice Department lawyers to take witnesses' depositions in the Soviet Union. Ryan said a U.S. magistrate and defense counsel could participate and that the examinations and cross-examinations would be video-taped for showing at a trial.

The special investigations office also has made arrangements with Israeli authorities to interview Jewish survivors of the Holocaust who immigrated here after the war and to send some of them to the United States as prosecution witnesses.

The special investigations office, with a staff of 50 and a budget of $2.3 million, took over from a small office in the Immigration and Naturalization Service that, with a budget of $90,000, opened some cases against suspected war criminals but had yet to deport any of them.

Rockler's office inherited 12 pending deportation cases and in the past two months has filed four more. He said that in the next year the Justice Department plans to dispose of all the inherited cases, and that it will begin work on 225 to 250 files that have accumulated over the years. Some of the files, he said, consist of "the thinnest sort of evidence" and will never be prosecuted.

The task is made more difficult, Rockler said, because the suspects range in age from 60 to 80 years, and appeals can stretch an average case out five years or more.

"In almost every case, we're racing against mortality," he said. "We're working at a distance of 6,000 miles and with courts and personnel who have no idea what World War II was all about."

Israel has long pressed the United States to adopt a more assertive program against former Nazis living in the United States and officials here welcomed the effort being made by Rockler's office, although they have complained privately that it should have been begun long ago.