President Reagan defended the ethical record of his administration last night at a nationally televised news conference, saying that he has "every confidence" in the integrity of embattled Attorney General Edwin Meese III and charging that critics are creating a "kind of lynch-mob atmosphere" in pre-judging Meese and other officials.

While expressing trust in Meese, who has worked under him for more than 20 years, the president declined to discuss the attorney general's role in a controversial Middle East pipeline project on grounds that it is being investigated by an independent counsel. Reagan said he had "no recall of knowing anything about this pipeline plan until fairly recently." The pipeline was never built.

At his first news conference since Oct. 22, the president also said that "we've never let up and we never will" in efforts to free the nine Americans held hostage in Lebanon. He defended the decision to send Lt. Col. William Higgins to Lebanon as part of a U.N. peace-keeping force, saying that Higgins -- who recently was abducted -- had volunteered for the position and that he realized it was "a dangerous business."

Reagan said "we have to have confidence" in people such as Higgins, once an aide to then-Secretary of Defense Caspar W. Weinberger, adding that "someone would have a hard time getting secrets that could harm this country from a person of that kind."

Reagan was critical of Republican presidential candidate Pat Robertson for saying that his Christian Broadcasting Network once knew the location of hostages in the Middle East.

"Isn't it strange that no one in our administration was ever apprised of that?" Reagan asked. "We have tried our best and through every kind of channel to establish their whereabouts. . . . if he thought that he knew, he kept it to himself."

Reagan, who has said that he is neutral in the Republican race, came to the aid of Vice President Bush on an issue that has been politically troublesome to Bush. The president said Bush is correct in claiming that he expressed "reservations" about the sale of U.S. arms to Iran but declined, as Bush has done, to provide details of those objections.

The president had given a different answer when the same question was asked at the end of a news conference last March 19. Asked then whether the vice president had joined Weinberger and Secretary of State George P. Shultz in expressing reservations about the arms deal, Reagan replied tersely, "No."

Aides have said that Reagan privately favors Bush for the Republican presidential nomination. Some of these aides have said Reagan was disturbed by the attempt of Sen. Robert J. Dole (R-Kan.), who also is a presidential candidate, to press Bush on the Iran arms-sale issue before the Iowa caucuses.

The ethical problems of present and former administration officials was a recurring theme at a news conference, the 43rd of Reagan's presidency, that ranged over many issues without going deeply into any. Reagan answered most of the questions evenly, but he showed a spark of anger when asked whether loyalty to his subordinates is more important than the perception that members of his administration are above reproach.

Reagan said he does not favor "violations of laws or ethics at all" but that members of his administration have been "smeared nationwide" by critics operating on the premise of "guilt by accusation." As examples, he cited the cases of former secretary of labor Raymond J. Donovan and former National Aeronautics and Space Administration chief James M. Beggs, who he said have been "completely cleared" by juries after being unfairly accused.

The president did not mention the six present or former prominent administration officials who were convicted or pleaded guilty to charges against them. The first of these was Rita M. Lavelle, head of the toxic-waste cleanup program of the Environmental Protection Agency, who was convicted in 1983 of lying to Congress and obstructing a congressional inquiry. The most recent conviction was of former White House political director Lyn Nofziger, who was found guilty this month of illegally lobbying administration officials.

When asked whether the Democrats would be able to use ethics issues effectively against Republican candidates this year, the president said, "I don't know whether they're going to be used effectively or not; I know they're going to be used." Without discussing the issue further, the president then accused the Democrats of misrepresenting the economic record of his administration.

Reagan opened his news conference with a prepared statement in which he repeated his support for the Nicaraguan contras and accused the Marxist Sandinista government of the country of not living up to promises to restore freedom and democracy to Nicaragua. The president did not explicitly choose between rival Democratic and Republican proposals in the House that would provide humanitarian aid to the contras, but he said the aid should be delivered through the Central Intelligence Agency, a method that the Democratic plan would prohibit.

When he was asked whether it is worth giving humanitarian aid to the contras without providing military assistance, the president said "anything that will keep the freedom fighters as a pressure on the Sandinistas is worth doing."

In his opening statement Reagan said he has received "encouraging" reports from Shultz on his recent trip to Moscow and said the secretary of state is now traveling to the Middle East "to see if practical and real progress can be made that provides a pathway to a comprehensive settlement. . . . "

Asked whether he condemns the treatment of Palestinians in Israeli-occupied territory on the West Bank, Reagan sidestepped the question by saying "we don't support that sort of thing" but adding that "there is every evidence that these riots" against Israeli rule "are not just spontaneous and home-grown." The president refused to spell out his evidence or say who he thinks is provoking the riots.

Reagan also refused to say whether the United States would be willing to drop the prosecution of Panama strongman Gen. Manuel Antonio Noriega, who has been indicted by a U.S. grand jury on drug charges, if Noriega stepped down.

"What we would like to see is a return to democracy and a civilian government in Panama and not this domination by literally a military dictator," Reagan said.

The president declined to say whether he will reach a finding that Panama has done everything in its power to control illegal drug traffic, a certification that would make Panama eligible to receive economic aid. Pressure against the recertification has been building within the administration and on Capitol Hill.

On the hostage issue, which has been especially troublesome for his administration, Reagan said attempts to free or even locate Americans who have been held in Lebanon for up to three years have been "very frustrating."

He said the administration is aware that "unwise action on our part could bring about some harm to the hostages, but we've never let up, and we never will, in trying to obtain the freedom of all the hostages."

Staff writer David Hoffman and staff researcher Michelle Hall contributed to this report.