CIA Candidate May Face Fallout on Iran-Contra Case : Perjury probe: Officials say Robert Gates recently testified to grand jury on scandal. Questions about his role sank nomination four years ago.

WASHINGTON —  Robert M. Gates, the leading candidate to be the next director of the CIA, recently testified before the Iran-Contra grand jury, according to officials familiar with the investigation--an appearance that could complicate the decision facing President Bush on whether to tap Gates as the nation’s next intelligence chief.

According to the sources, Iran-Contra special prosecutor Lawrence E. Walsh is probing possible perjury by officials during the scandal. Gates, however, is not a target of the probe and was called only as a witness, the sources said. Nonetheless, Gates’ testimony before the grand jury is a sensitive issue because it could raise the question of Gates’ knowledge of the Iran-Contra affair--a chapter of history that White House officials have been eager to avoid reopening.

Questions about Gates’ knowledge of the scandal and his testimony about it sank his nomination to head the CIA four years ago. And at least some members of the Senate have warned White House officials that although Gates’ image is now far better on Capitol Hill, his nomination could have unpredictable consequences, reopening issues that Bush has been happy to have closed for the last several years.

Walsh’s spokeswoman, Mary Belcher, declined comment when asked about Gates’ appearance before the grand jury. “I cannot comment on any grand jury matter,” she said.

But sources familiar with the investigation say that one of the officials Walsh is known to be focusing on is a close former aide to Bush--Donald P. Gregg, who was Bush’s top national security aide when Bush was vice president and is now U.S. ambassador to South Korea. Several witnesses have testified over the years that they told Gregg about efforts to supply Nicaragua’s anti-government Contra rebels. He has denied the accounts.

Bush, for his part, consistently has denied that Gregg ever told him about the Contra aid efforts that were being headed by National Security Council staff member Oliver L. North.

At the time, federal officials were forbidden by law to be involved in efforts to provide military aid to the rebel forces.

Walsh is believed to be close to wrapping up his investigation and has called a wide array of current and former CIA officials before the grand jury. Prosecutors are concentrating on the truthfulness of statements made to investigators by Gregg and several mid-level CIA officials who were involved in the efforts to aid the Contras.

Four years ago, Reagan nominated Gates to head the CIA, but was forced to abandon the nomination after several senators raised questions about whether Gates had accurately testified about his knowledge of the affair and the efforts to cover it up.

During the last nomination battle, questions about Gates’ role focused on two issues--whether he had been wrong in failing to inform Congress about the CIA’s role in the sale of arms to Iran and whether he had helped former director William J. Casey mislead Congress about the agency’s role in aiding the Contras. At the time, Gates was the CIA’s second-ranked official.

Gates’ defenders argue that Casey, who died a few months after the scandal became public, had used Gates as a “front man.” But during the hearings, Gates’ opponents charged that he had allowed his concerns about protecting his career to overweigh his obligation to report potential wrongdoing to Congress.

In October, 1986, for example, shortly after a plane carrying arms to the Contras was shot down over Nicaragua, Casey falsely testified to Congress that the CIA had no involvement with the supply flights. Gates, who accompanied Casey to Capitol Hill, said nothing although he already had received some information to contradict what Casey had said.

Gates later testified that the information he had was too sketchy for him to say anything about it. But several senators challenged him on that point.

In addition, one of Gates’ chief questioners at the time, Sen. Arlen Specter (R-Pa.), also charged that Gates had given inconsistent testimony during later appearances before congressional committees, changing his account as more facts about the scandal became public knowledge. Gates insisted that any inconsistencies in his testimony were the result of innocent mistakes.

White House officials say Bush has not yet reached a decision about whether to nominate Gates to the CIA job. Secretary of State James A. Baker III reportedly has been pushing one of his top deputies, Undersecretary of State Robert M. Kimmitt, for the post, and Bush is known to have several other potential candidates under consideration. Nonetheless, officials say, Gates remains the strong front-runner, and a decision could come this week.

Staff writer Robin Wright contributed to this story.