Careless remarks by President Reagan inadvertently undercut U.S. efforts to deal with the fraud-tainted Philippine election, according to administration officials looking back on a week of conflicting and confusing statements.

Officials said a communications failure beginning with the president caused the confusion, rather than the kind of deep-seated divisions that exist among Reagan's top advisers on many other issues.

In this case, these advisers -- Secretary of State George P. Shultz, Defense Secretary Caspar W. Weinberger, Central Intelligence Agency Director William Casey and national security affairs adviser John M. Poindexter -- shared similar reservations about Philippine President Ferdinand Marcos and had for months wanted the Reagan administration to push Marcos toward reforms and fair elections, the officials said.

Reagan accepted the policy recommendations of his advisers in authorizing the release of carefully written White House statements Jan. 30 and Feb. 11 intended to emphasize U.S. support for fair and credible elections in the Philippines.

Nonetheless, remarks by Reagan and White House chief of staff Donald T. Regan -- before and after the election -- appeared to tilt U.S. policy toward Marcos, generating emotional responses in the Philippines, dismay within the Reagan administration and growing pressure from key members of Congress for decisive U.S. condemnation of election fraud.

In a related development today, House Foreign Affairs Committee Chairman Dante B. Fascell (D-Fla.) and Senate Appropriations Committee Chairman Mark O. Hatfield (R-Ore.) joined the chorus of congressional leaders calling on Reagan to take a tough stand against election fraud in the Philippines Details, Page A21 .

Reagan's advisers suggested at the beginning of the week that the United States should proclaim strict neutrality while criticizing vote fraud and urging in general terms that the will of the Filipino people should be respected. Officials said they hoped this policy would avoid encouraging street violence but also would send a disapproving message to Marcos.

The policy advice was incorporated into a written statement issued Tuesday afternoon by the White House. That statement asserted the election was "flawed by reports of fraud which we take seriously," and announced that Reagan was sending former Mideast envoy Philip C. Habib to the Philippines as a special emissary.

But the impact of the carefully worded statement was undermined by Reagan's news conference comment that night that there may have been fraud "on both sides."

Officials familiar with the president's thinking said Reagan was told before the election that the Philippines had a history of widespread election fraud. Advisers say that Reagan, early in the week, seized upon a story he had heard or read about ballots cast for presidential candidate Corazon Aquino being found in a ditch.

On Monday, in an interview with The Washington Post, Reagan first showed a disinclination to blame Marcos for the fraud, when he responded to a question about the future legitimacy of the Marcos government.

After saying that there had been fraud in some U.S. elections, Reagan added, "And I don't know the extent of this over there . . . . do we have any evidence that it's all been one sided, or has this been sort of the election tactics that have been followed there?"

On Tuesday morning, Reagan was briefed twice on the Filipino elections. The first meeting was with Shultz and Weinberger, with chief of staff Donald T. Regan present. The second, with Regan and White House counsel Fred Fielding in attendance, was with Senate Foreign Relations Committee Chairman Richard G. Lugar (R-Ind.), and Rep. John P. Murtha (D-Pa.), who headed the observer team at the elections. In both meetings, officials said, Reagan was told the election was seriously tainted, although Lugar also said many reports of fraud couldn't be verified.

"Nonetheless, the message of fraud was unmistakable," one official said. "The president said very little but listened intently."

After the second meeting, a team of officials put final touches on the statement. It was drafted by State Department officials and Fielding and approved by Shultz and Poindexter. Reagan was shown the statement by Regan, agreed to issue it and went off to rehearsal sessions with a number of advisers.

One official who helped in the preparation said it was "assumed" that Reagan wouldn't talk again about fraud on both sides as he had the day before because Lugar and Murtha had fixed most of the blame for misconduct on the Marcos side. But White House officials preparing Reagan were still concerned that the message he would give might be "misinterpreted," a phrase often used to blame the news media when the president -- frequently called the "Great Communicator" -- strays from his prepared guidance.

At the news conference, Reagan stuck to this script when first asked about the election, saying that the United States was "neutral" and would wait to make any assessment. But when reporter Mike Putzel of the Associated Press persisted, Reagan reverted to his Monday answer and said there was "the possibility of fraud, although it could have been that all of that was occurring on both sides."

Some officials were critical in retrospect of chief of staff Regan, who had said on television several days before the election that the administration would have to do business with Marcos even if he were elected by fraud.

"Don is not sophisticated about foreign policy issues and tends to say what comes into his head," said one senior official. "He certainly didn't explain the delicacy of the situation to the president."

But others who have been around Reagan for a long time said that what was in the president's head caused the difficulty.

"Reagan deep down didn't want to blame Marcos for what he was told was happening in the Philippines," said one official. As a result, he wound up excusing him.