D.C. mayoral aide Joseph R. Yeldell admitted yesterday that he had misled city auditors who were investigating his relationship with millionaire Dominic F. Antonelli Jr. and that he had submitted inaccurate financial statements to government and private agencies.

Testifying for the second day at his bribery and conspiracy trial, Yeldell, the former head of the city Department of Human Resources acknowledged under stiff cross-examination that he had made statements that were "embellished," "not relevant" and "not accurate" when he was interviewed in March 1977 by investigators from the D.C. Municipal Audit Office who were probing his ties with Antonelli and DHR's leasing practices.

In response to one question by Assistant U.S. Attorney Richard L. Beizer about apparent discrepancies in a personal financial statement submitted by Yeldell to a Washington bank, Yeldell replied, "I may have made a mistake." Yeldell's 1974 financial statement had listed bank debts amounting to $8,500 when he acknowledged, his outstanding bank debts at the time totaled more than $15,000.

Throughout yesterday's cross-examination, Yeldell repeatedly said he could not recall key events and conversations, some of which had been recounted by previous witnesses in the U.S. District Court trial. At times, he said he had not examined financial and other statements that bore his signature. Again and again, he disputed or contradicted testimony by his former DHR aides and other officials.

THe prosecution appeared to hammer at apparent inconsistencies in Yeldell's testimony in an attempt to damage his credibility in the eyes of the jury. The cross-examination is expected to resume this morning, and the prosecution appears likely to point to additional discrepancies between Yeldell's testimony and his statements during the tape-recorded 1977 interview with the municipal auditors.

Despite the sometimes sharp prosecution questioning. Yeldell, who is now on unpaid leave from his most recent job as a top aide to Mayor Walter E. Washington, appeared to remain relatively relaxed, frequently responding in an easygoing manner without any display of anger. Antonelli, a real estate developer and parking company owner, maintained an impassive expression throughout Yeldell's nearly five hours of testimony yesterday.

The two men are charged in a grand jury indictment with conspiring corruptly to arrange a highly profitable 20-year DHR lease of a two-story office building at 60 Florida Ave. NE from a partnership controlled by Antonelli. In exchange for Yeldell's help in concluding the $5.6 million lease, Antonelli is alleged to have secretly given Yeldell a $33,000 loan after helping him obtain a series of previous short-term loans from Madison National Bank, in which Antonelli is a stockholder and director.

At one point, Antonelli's chief defense lawyer, Edward Bennett Williams, threatened to ask Judge Gerhard A. Gesell to declare a mistrial because of a prosecution question dealing with Doctors Hospital. Antonelli has been a stockholder and director of the hospital's parent corporation, and Yeldell has issued controversial government permits for the hospital. Williams, who had contended that the question was "prejudicial" to Antonelli, later withdrew his threat and merely objected to the question.

Yeldell's acknowledgement that he had given misleading information to the city auditors appeared significant party because, as the former DHR chief conceded yesterday, the auditors had submitted written questions in advance to his lawyers and allowed time for Yeldell to formulate answers before undergoing the tape-recorded interview.

The auditors' investigation had been conducted at a time when Mayor Washington's government was enmeshed in a widening controversy that had stemmed, in part, from disclosures by The Washington Post about Yeldell's efforts to arrange a DHR lease for Antonelli. The mayor later cited the auditors' public reports - some of the auditors' findings were never made public - as a basis for returning Yeldell to a key government job, saying that no evidence had been turned up that would prevent Yeldell's reinstatement. Yeldell had previously been suspended by the mayor for 120 days.

Yeldell's clearest admission yesterday that he had misled the auditors was prompted by a series of questions by Assistant U.S. Attorney Beizer about Yeldell's short-lived decision in October 1975 to call off negotiations for the proposed Florida Avenue lease. According to court testimony, Yeldell temporarily halted the lease negotiations after the D.C. Department of General Services, which was then handling lease arrangements for DHR, had decided to reject Antonelli's proposals and seek to conclude a lease with another businessman, Emanuel Logan.

When one of the audit investigators asked Yeldell's to explain his October 1975 decision, according to court evidence, Yeldell responded by citing a series of factors that, he acknowledged yesterday, he did not uncover until long after the decision was made. Most of these dealt with uncertainties about Logan's financial resources and real estate experience.

Yeldell never flatly conceded that he had not told the auditors the truth. Instead, he contended that he had sought to "defend my position" by citing information he had obtained at a later time to justify his earlier objections to Logan's offer. "These things were all ture, but they occurred at a later time," he testified. "These statements are all accurate, but they are not accurate as of October 1975."

At another point in the tape-recorded interview, Yeldell had said that he and Antonelli did not become friends until 1973 - a time when Antonelli first helped Yeldell get a loan. Both men have testified, however, that they have been friends since about 1967. When asked about this apparent inconsistency yesterday, Yeldell conceded, "I clearly know Mr. Antonelli before 1973." He acknowledged that his statement to the auditors might be viewed as a "mispresentation."

In his testimony yesterday, Yeldell also contradicted another statement he had made in the interview with the auditors by describing a meeting he had had with Antonelli on Dec. 22, 1975. Yeldell told the jury that he had arranged the meeting on the same day - Dec. 19, 1975 - as DHR was given independent powers to lease privately owned buildings. He testifed that he had informed Antonelli at the meeting of DHR's new powers and invited Antonelli to submit a lease proposal for the 60 Florida Ave. NE building.

In his interview with the auditors, Yeldell had firmly denied that he had notified Antonelli of DHR's newly obtained leasing powers at any time before Antonelli submitted a lease proposed to DHR on Dec. 26, 1975. Yeldell's description of the Dec. 22, 1975, meeting was given in response to questions from his lawyer, John A. Shorer Jr.The prosecution has not yet dated his apparently contradictory statements about the December 1975 events, but the issue appears likely to be raised during cross-examination today.