Environmental Protection Agency Administrator Anne M. Burford came under increasing pressure to resign yesterday as White House officials compiled a list of possible replacements for her and senior EPA aides.

Burford, described by associates as "under enormous stress," told reporters that she had no plans to resign. She spent yesterday defending the EPA's 1984 budget proposal before a House Appropriations subcommittee.

"The agency is in a very difficult situation," Burford said. "I hope to provide the leadership to the talented staff . . . to make sure they can go on about the jobs that we all came to do--which is environmental protection."

Several of Burford's aides said yesterday that she has urged President Reagan to drop his claim of executive privilege and give Congress unrestricted access to any and all EPA documents it is seeking for several investigations.

Saying that Burford has opposed the executive-privilege claim for months, one of her aides said: "Every fiber of her political body told her the only thing that could come from withholding the documents would be trouble for the agency."

Several administration officials said that senior White House aides now consider Burford a serious political liability to the president and are signaling her to resign, even though Reagan has expressed confidence in her publicly.

The officials said these signals include recent on-the-record comments by White House chief of staff James A. Baker III and Cabinet secretary Craig L. Fuller that the White House has not ruled out the option of firing Burford.

"The people at the White House whose business it is to look after Ronald Reagan now believe she has to go," one administration official said yesterday. "These are the straight political types who don't normally concern themselves with the environment. It's not a question of whether she's right or wrong or whether there's a moral issue here. She's a liability."

An aide to Burford said she was informed last night that the Justice Department will no longer defend her against contempt-of-Congress charges brought by the House last year when she cited executive privilege and withheld certain EPA documents subpoenaed by a House subcommittee.

"She's being cast loose in an attempt to make her resign," the official said, noting that Burford withheld the disputed documents--against her wishes--under orders from the president, who acted on the advice of the Justice Department.

Officials said the White House list of possible replacements for Burford, which they described as a "contingency plan" for her departure, includes John R. Quarles, who was deputy EPA administrator in the Nixon and Ford administrations, and Stanley Legrow, a former EPA official who recently moved here from California.

Quarles and Legrow, both attorneys, are considered by many members of Congress, environmental groups and administration officials to have moderate views on environmental issues. Quarles is a lobbyist for an industry group that supported the administration's unsuccessful bid to relax portions of the Clean Air Act in the 97th Congress.

Sen. Rudy Boschwitz (R-Minn.) yesterday became the first Republican senator to call for Burford's ouster. He asked Reagan to replace her "with a politically independent person of nationally recognized scientific qualifications."

As the pressure on her mounted, Burford moved on several fronts to try to bolster the credibility of the EPA, which is the subject of investigations by six congressional subcommittees, the FBI and the White House. They are probing charges of conflict of interest, political favoritism and wrongdoing by agency officials, mainly in the program to clean up the nation's most dangerous hazardous waste dumps.

Burford's aides appeared eager yesterday to tell reporters that she blames the Justice Department for most of the agency's current problems and believes that Justice erred last year in advising her to cite executive privilege rather than cooperate with the House panels.

After Burford withheld the documents, she was cited for contempt by the full House. At the time, the congressional probe of the EPA's hazardous waste program was beginning, and many agency officials now blame the contempt citation for triggering the current controversy.

In another effort to shore up public confidence in the agency, Burford this week directed her chief of staff, John E. Daniel, to halt all out-of-court agreements with firms responsible for creating dangerous dumps. Daniel called the order a response to congressional accusations that the EPA has struck "sweetheart deals" with polluters rather than suing them for the full cost of cleaning up their toxic wastes.

"This is being done out of an excess of caution to reassure the public and members of Congress," Daniel said. "In the present climate, it's prudent to take this approach."

Daniel added that he is unaware of any "sweetheart deals" and that the new policy will probably be only temporary.

Only 11 of the Reagan administration's 41 cleanup agreements with companies that dumped hazardous wastes have been reached without court approval, an EPA spokesman said. One of the agreements under heaviest congressional attack, the $7.7 million settlement for the cleanup of a Seymour, Ind., dump, was approved by a federal judge.

It was also learned yesterday that the FBI has broadened its investigation to include congressional charges of wrongdoing by Burford and EPA general counsel Robert M. Perry. The FBI is also investigating alleged conflicts of interest by James W. Sanderson, the Denver attorney who worked as a consultant to Burford for several months and later was one of her deputies.

The FBI investigation earlier was said to be focusing on ousted hazardous waste control program chief Rita M. Lavelle and charges of possible conflicts of interest and the shredding of documents in her office.

Daniel said Burford welcomed the broader probe in hopes of "clearing the air" of the proliferating charges of wrongdoing that, he said, have hampered the agency's work.

Sources said the FBI is investigating charges that Perry perjured himself under oath before a congressional subcommittee last year when he denied keeping "green books" of derogatory information on employes who were out of favor.

Agents are also looking into congressional charges that Burford personally held up $6.1 million for the cleanup of a dangerous toxic dump in California, the Stringfellow Acid Pits, for political rather than health and safety reasons, sources said.

Burford has emphatically denied the charge that she delayed the project for fear that it would help the Senate campaign of then-Gov. Edmund G. (Jerry) Brown Jr., a Democrat who might have claimed credit for bringing in the federal dollars.

Administration sources said the Sanderson probe focuses on charges that he used his position at the agency to benefit his clients, which include the Denver Water Board and Chemical Waste Management Inc., the largest hazardous waste disposal firm in the country.

The sources said the FBI has questioned EPA officials about the agency's decision to speed consideration of a permit for the Vulcanus I, a ship used by Chemical Waste for burning toxic wastes at sea.

Sanderson has said he "walled myself off" from matters that affected his clients, but several agency officials said he took part in discussions of water and hazardous waste policies.

EPA officials also said yesterday that they are seeking a $126,000 fine against the Thriftway Co. for exceeding the EPA limits on lead in gasoline. The action, filed last November, contrasted with a reported assurance Burford made to Thriftway officials in 1981 that they were free to exceed the limits because she planned to relax them. She has since said she did not "intend or authorize people to break the law."

But Thriftway is challenging the agency action as a violation of Burford's promise. In a Feb. 16 letter to Perry, Thriftway lawyer William F. Cockrell said his company's action resulted "solely because of, and in complete reliance on, Administrator Gorsuch's Dec. 11, 1981, unequivocal commitment that EPA would not enforce the lead standards which otherwise would apply to Thriftway during the period that EPA was reconsidering its lead phasedown regulations." (Gorsuch was Burford's name before her recent marriage.)

In response to public pressure, the EPA did not lower the standard after all.