The confrontation between Congress and the Reagan administration over the conduct of the Environmental Protection Agency escalated yesterday when a House committee chairman demanded that the FBI investigate the shredding of copies of documents subpoenaed by Congress.

In a harshly worded letter, Chairman James J. Howard (D-N.J.) of the House Public Works and Transportation Committee called on Attorney General William French Smith to direct FBI agents "to take whatever steps are necessary to insure the integrity of these subpoenaed records and to thereby investigate the circumstances surrounding their destruction."

Howard reminded Smith that President Reagan acted on Justice Department advice in ordering EPA Administrator Anne M. Gorsuch to withhold the subpoenaed documents from Howard's committee. This led the House to vote a historic contempt-of-Congress citation against Gorsuch.

"That your department has permitted circumstances to exist which have resulted in the destruction of subpoenaed documents raises the most serious questions concerning the responsibility of the department for these recent events," Howard told Smith in the letter.

Officials of the EPA yesterday repeated their assertions that they did nothing illegal in destroying copies of the documents, which were subpoenaed by the House committee for an investigation into charges of conflict of interest, political favoritism and mismanagement of Superfund, the EPA's $1.6 billion hazardous-waste cleanup program.

But Howard charged in an interview that "The conduct of this entire affair by the White House, the Justice Department and the EPA is beginning to smell suspiciously like a criminal cover-up of wrongdoing in the enforcement of the hazardous-waste laws."

Noting that the subpoena covered duplicates of the documents as well as originals, Howard said, "If I were to sum it up in one word, it might be Sewergate."

The disclosure of the shredding came after a week of escalating turmoil at the EPA, beginning with President Reagan's firing of Rita M. Lavelle, who was chief of the agency's hazardous-waste enforcement program. The agency now faces six congressional investigations and increasing expressions of concern from the White House.

John Daniel, Gorsuch's chief of staff, said yesterday that the week's disclosures of shredding and other events in the agency are "unsettling" to top agency officials, "and we are as concerned about them as Congress." He said Gorsuch aides are looking into the shredding "to satisfy ourselves as to what exactly were the controls on those documents" that were destroyed.

Daniel confirmed that no log was kept of documents that were shredded. He said he had confirmed reports that Lavelle's appointment calendars, along with two boxes of her personal documents, were removed from the agency shortly after her departure.

"We're still looking for it, but I am given to understand that the calendar is not there," Daniel said. A House committee had requested the calendar as part of an investigation of Lavelle.

Two automated shredders were moved to the hazardous-waste program office on Jan. 4, three weeks after Gorsuch was cited for contempt of Congress. EPA spokesman Rusty Brashear said the move was "non-sinister" and that Daniel did not learn of it until Thursday, when the shredders were removed.

However, congressional sources said that Daniel was telephoned Tuesday evening by a congressional investigator, who told him of the shredders and expressed concern about the safety of the documents.

Asked about the discrepancy, Daniel said the investigator told him on Tuesday that there was a shredder in Lavelle's office. After checking the report, he said, "I ascertained there was not . . . . It was not until yesterday Thursday that I learned that there was indeed a shredder in the document room" in Lavelle's suite of offices.

Meanwhile, EPA officials attempted to explain why agency spokesmen had said Thursday that duplicates of "sensitive" documents being withheld from Congress had been run through the shredder, although Daniel said in a prepared statement that the agency had destroyed only "copies of documents other than enforcement-sensitive documents that were in the file."

Brashear and two aides, who faced a barrage of calls from reporters seeking explanations for the discrepancy, said the agency has interpreted the subpoena for "duplicates" to cover only one copy of each document, unless additional copies bear notations or any extra markings.

House leaders have said they need duplicates as well as originals in order to examine all marginal comments by key agency officials on documents used in making decisions on hazardous-waste cases. The House leaders have charged that the EPA concluded "sweetheart" deals with companies responsible for major dump sites, and that some officials had improper ties with those firms.

Gorsuch has denied the charges emphatically.

"Congress has legitimate concern about these documents, or they would not have requested them," Daniel said. "They're making a legitimate request to know the whereabouts of those documents, and we are asking those questions as well."

Reports of the shredding appeared to have intensified congressional suspicions about EPA, which were fed during the week by reports of connections between administration officials and companies responsible for several of the nation's most dangerous hazardous waste dumps.

The White House moved to distance itself yesterday from the EPA when reporters inquired about the use of the shredders. "EPA can tell you what they were doing with shredders," said White House deputy press secretary Larry Speakes. He added that the White House has been "assured" that necessary documents "are preserved."

Congressional critics said the shredding incident was reminiscent of a memo written last fall by an EPA regional inspector general, urging his subordinates to "purge" their files of material "that could prove embarrassing to outsiders."

Warning of the dangers that his staff faced if they received requests for documents under the Freedom of Information Act, James J. Conn Jr. had told his staff to "think about what to get rid of, before an FOIA request catches us with our pants down . . . . We can no longer lock materials in our desks and private workpapers and hope to exempt them from disclosure."

The memo was sent after an investigator's notes were leaked to a congressional committee, which caused embarrassment to the agency.

Kirk O'Donnell, general counsel to House Speaker Thomas P. (Tip) O'Neill Jr. (D-Mass.), said yesterday that House leaders are especially angered by the shredding of documents because the Justice Department has attempted to block U.S. Attorney Stanley Harris from taking the contempt case against Gorsuch before a criminal grand jury. Federal contempt procedures require the U.S. attorney to take this step, O'Donnell said.

"The focus is on Justice and the U.S. attorney. They clearly have been negligent in this matter. It is inexcusable that they have allowed the integrity of these records to be compromised," O'Donnell said.

Deputy Attorney General Edward C. Schmults was to have proposed a compromise to the House yesterday to try to resolve the contempt case short of criminal proceedings. But negotiations were postponed because Rep. Elliott H. Levitas (D-Ga.), chairman of the Public Works and Transportation oversight subcommittee that issued the subpoena for the documents last October, was stranded in Atlanta because of the snowstorm.