The White House yesterday released hundreds of pages of documents prepared by President Carter's staff for his 1980 debate with Ronald Reagan that were found in the files of two Reagan aides, along with an account of a Carter campaign "brainstorming session . . . from a source intimately connected to a Carter debate staff member."

Former Carter press secretary Jody Powell said last night after reviewing the documents that "it appears that the Reagan campaign had an ongoing flow of information from within the Carter White House."

But President Reagan later minimized the importance of what his campaign aides received, saying in his news conference last night that he "never saw anything of the kind."

Joking and chuckling during his responses to several questions about the matter, he added, "It seems strange to me, since I was the debater, no one on our side ever mentioned to me anything of this kind, or that they had anything or told me any of the things that supposedly were in there."

Pressed on whether he considered the actions of his campaign aides to be ethical, Reagan said that he does not think "unethical things should be done" in political campaigns but that he would not reprimand or take any action against any of his advisers. The White House has not said how the documents released yesterday found their way to the Reagan campaign.

Among them was a memo addressed to then-Reagan campaign adviser David R. Gergen, now White House communications director, from a Reagan campaign volunteer. The memo contained Carter debate preparations purportedly discussed at a Carter staff meeting.

Dated Oct. 21, 1980, and sent to Gergen by Wayne H. Valis, the memo said: "These notes are based on a Carter debate staff brainstorming session--middle-level types--nothing spectacular, but interesting--from a source intimately connected to a Carter debate staff member. Reliable. I gave a copy to Jim Baker."

The documents and the memo to Baker, now White House chief of staff, were discovered Monday in the Reagan campaign files of Gergen, who had previously said he did not recall having seen any of the Carter material, and Frank Hodsoll, now chairman of the National Endowment for the Arts. They coordinated and edited the material prepared for Reagan in the presidential campaign debate that occurred just a week before the 1980 election.

Office of Management and Budget Director David A. Stockman, who rehearsed Reagan for the debate with Carter, also acknowledged in a memo released yesterday that he received from Reagan campaign officials additional materials apparently from the Carter camp. These were not made public yesterday.

Powell said some of the materials obtained by the Reagan campaign had originally been prepared for Walter F. Mondale, then vice president, in late September, 1980, in anticipation of a debate between Mondale and Republican vice presidential nominee George Bush. That debate never occurred.

Other documents released by the White House yesterday were Carter staff drafts for the briefing book for Carter's Oct. 28 debate with Reagan, Powell said. These drafts contained hundreds of pages of questions and answers on foreign and national-security issues that Carter's staff prepared for him to use against Reagan.

Stockman said in his memo to White House counsel Fred F. Fielding yesterday that what appeared to be Carter briefing papers on domestic issues also was included "in the large package of Xeroxed pages delivered to me by the Reagan campaign" before he rehearsed Reagan for the debate.

When a reporter asked Reagan last night whether it was proper for his campaign aides to have used the Carter documents, rather than returning them to the Carter White House unread, Reagan referred to newspapers' publication of the Pentagon Papers outlining the history of the U.S. buildup in Vietnam.

"It probably wasn't too much different from the press rushing into print with the Pentagon Papers, which were stolen," Reagan said. "And they were classified. And it was against the law."

Beginning with the first question of last night's news conference, reporters repeatedly pressed Reagan on whether he thought it was unethical for his aides to have accepted and utilized Carter's private debate strategy memos, regardless of legality.

At one point, a reporter probed the ethics question by asking Reagan if his campaign aides should have "followed the example that is known about in another case," that of Arizona Democratic Rep. Morris K. Udall's 1976 primary campaign against Carter, "where . . . material came into someone's possession and it was returned unopened."

Reagan answered: "Well, I don't know that it came in any kind of cover or anything to denote what it was."

The sixth time a reporter asked about "the ethical question," Reagan replied: "The ethical question? I think that campaigning has always, in the eyes of the people, had a kind of double standard. And I have deplored it . . . . I don't happen to believe politics should have a double standard.

"No. I think it should be above reproach. And there shouldn't be unethical things done in campaigns, even such things as accusing the other candidate of being a racist, and things like that," he said in an apparent reference to Carter's campaign claim that a Reagan victory would divide black against white, Christian against Jew.

Reagan said he did not know how his staff obtained the Carter documents and, asked specifically if they had been stolen, replied:

"Is it stolen if someone hands it to you? We don't know how it was obtained . . . . All my people who have any knowledge at all of this have been told that they are available to the Justice Department, and I told the Justice Department they are all available for any questioning they want to do."

On Monday, the White House pointedly referred to the Justice Department "monitoring" of the case, declining to use the word "investigation."

But last night, pressed by a reporter who asked if this meant Justice was indeed conducting an investigation, Reagan said: "Yes, I've called it 'monitoring,' but an investigation is . . . what it amounts to. I've said to find out if there was any wrongdoing and take action."

The materials released yesterday by the White House were not identical to the final debate briefing book given Carter by his advisers. Copies of that book were given this week by Carter's former advisers to the White House and reporters.

But the president's top advisers acknowledged in letters made public yesterday that the materials received by the Reagan campaign in 1980 were apparently lengthier, early versions of the final product that Carter's aides actually gave him in 1980. That was not mentioned by Reagan at his news conference, nor was it cited by reporters questioning him.

While all of the Carter staff documents made public by the White House dealt with foreign policy and national security, Stockman said in his memo to White House counsel Fielding that the portion of the final debate preparation book dealing with domestic issues "appears to be similar to the material I received" during 1980 debate preparations.

Citing the section of the final Carter book entitled "Carter Questions and Answers" on the "economy," "energy and environment," "overview," government" and "human needs," Stockman said:

"While this section appears to be in a different format, more tightly written and organized and more addressed to specific debating points than I recall, I would conclude that the substantive content . . . is similar to material made available to me prior to the debate rehearsals."

In those rehearsals of Reagan, Stockman played the role of President Carter while syndicated columnist George Will and current U.N. Ambassador Jeane J. Kirkpatrick played journalists questioning Reagan.

Among documents found in the files of Gergen and Hodsoll and released yesterday was one dated Sept. 29, 1980, and entitled, "Presidential Debates: Foreign Policy and National Security Issues."

Carter advisers said that was the working draft of the smaller, final version included in Carter's final briefing book, was dated Oct. 20, 1980, and was titled "Presidential Debate Briefing Papers: Foreign Policy and National Security."

It was prepared by two Carter National Security Council aides, Rick Inderfurth and Eric Newsom. Reagan's advisers, in their memos yesterday, acknowledged that Carter's final foreign-policy document seemed, in Stockman's words, "quite similar" to what they had received during the debate preparations.

Another document found in Hodsoll's files contained a series of additional questions on foreign affairs and defense issues. Powell said this was prepared for Mondale's use by Dennis Clift, Mondale's specialist on national security issues.

Seven days ago, Gergen wrote to Rep. Donald J. Albosta (D-Mich.), chairman of a House subcommittee investigating the affair, and said:

"I do not recall ever receiving or seeing a 'Carter debate book' or any other notebook from the Carter campaign. Had that occurred, I believe that I would remember it. It is possible that I did see some pages of 'Carter material' for a brief period, but I do not recall it . . . . I do recall hearing that some material from the Carter campaign was present in the Reagan campaign."

Yesterday, Gergen wrote: "Since responding to your letter last week, I have found that I made a mistake, and I want to correct the record with you and to convey to you my personal apology . . . . Mr. Chairman, that letter was written to you in good faith . . . . Unfortunately, I wrote that letter to you before completing a thorough search of all my files."

White House chief of staff Baker has said that he passed the Carter debate documents to Gergen and Hodsoll for use in preparation of Reagan's debate strategy.

Baker has said that he obtained them from William J. Casey, then Reagan's campaign manager and now director of the CIA. Casey reiterated in a memo to Fielding yesterday that he remembers nothing of the sort and added that he believes he would have remembered the documents had he seen them.

"I have . . . examined the pile of papers provided to the White House counsel's office by Francis Hodsoll and David Gergen," Casey wrote. "I do not recognize them as anything I have seen before.

"A great many papers came to my desk during September and October of 1980. Any pile of papers two inches high would almost certainly have been set aside to be passed along to others in the campaign.

"However, if papers headed 'Presidential Debates, Foreign Policy and National Security Issues' came in, I believe they would have caught my eye or would have been brought to my attention and I would not have forgotten, nor would I have forgotten if anyone came in and handed them to me."

Last night, Reagan expressed support for Casey. "I can understand his very well not having paid any attention," Reagan said of Casey. "He wasn't going to wade through a stack of papers. They didn't come in a binder or anything."

In an ABC News interview yesterday, former president Carter said the documents had been "very valuable . . . . For all I understand, this was a very serious loss to our campaign."

House Speaker Thomas P. (Tip) O'Neill Jr. (Mass.), however, told reporters that he did not favor a House inquiry into the matter and that Carter would have lost the election regardless of the briefing-book case. "Briefing book or no briefing book, our candidate was extremely unpopular in the last election," he said.

Last night, Reagan laughingly said, "I happen to agree with House Speaker Tip O'Neill . . . . I found he was speaking with words of profound wisdom."