D.C. Mayor Anthony A. Williams apologized yesterday for waiting until recently to disclose information about two consulting arrangements with city contractors that paid him $40,000 during his campaign and transition into the mayor's office last year.

"I should have disclosed the fact of my outside employment earlier and inadvertently failed to do so," Williams (D) said in a statement that was released as he filed details of his work for NationsBank and the Arthur Andersen & Co. accounting firm with the city's Office of Campaign Finance. "For this oversight, I am sorry."

Williams has said he took the work to provide his family with an income after he left his $118,000-a-year post as the District's chief financial officer to campaign for mayor. D.C. campaign finance officials are reviewing Williams's activities to check for, among other things, any violation of the city's conflict-of-interest laws. The statute prohibits officials from using public office to obtain financial gain for themselves or businesses with which they are associated.

Williams disclosed the consulting contracts in financial statements that all D.C. officials are required to file each May. His contracts came about after supporters at the Greater Washington Board of Trade asked several firms whether they could provide work for Williams during the mayoral campaign because he had said it would be a financial hardship for his family.

The financial disclosure statements that D.C. officials and candidates for office must file specifically state that any changes in income that occur within 30 days after a report is submitted must be reported immediately.

Williams turned in a financial statement on July 17, 1998, a month after he announced his candidacy. Less than two weeks later, on July 31, he signed a $30,000 contract with Arthur Andersen. The contract with NationsBank, for $10,000, was signed on Aug. 6, 1998, also within the 30-day window for disclosure.

The mayor first disclosed the agreements in forms filed this month, and when questioned by The Washington Post about the consulting work, he initially said he was under no legal obligation to elaborate on what he did for the two city contractors.

When the Office of Campaign Finance requested more details on the work, Williams agreed to provide them.

"I believe it is exceedingly important to disclose the facts related to work I conducted for the two firms during last year in order to demonstrate that nothing improper occurred," Williams said yesterday. "My work for those two firms did not involve their relationship with the District of Columbia."

But Williams, under his contract with Arthur Andersen, did meet with John L. Green, senior vice president of the Helix/Medlantic Healthcare Group, to discuss a bond financing deal involving D.C. government.

Green said Williams met with him and two other officials of the firm, now known as MedStar Health, for an hour to answer questions primarily on how to proceed with bond financing involving the District and a Maryland health authority.

"It did not focus on the District," Green said.

Green said Ira Goldstein, the senior partner at Arthur Andersen's Washington office who signed Williams's contract, had called him to say that Williams was with the firm and that it was "a possibility that Williams would be available to provide some assistance."

"When he mentioned it to me, I thought that was an excellent idea based on Williams's background [in municipal finance] in Boston and St. Louis," Green said. "We viewed it as an opportunity to get sophisticated advice."

At the time he met with Williams, Green was a representative of one of the District's major contractors. In 1998, the city's Medicaid program paid Washington Hospital Center -- which is owned by MedStar Health -- more than $30 million in fees for patient care.

Peggy Armstrong, the mayor's spokeswoman, said that at the time Williams believed that Helix/Medlantic did not have contracts with the city.

"They weren't talking about contracts with the city, but the process a local jurisdiction would use for bond financing," Armstrong said.

Arthur Andersen officials have said that Williams participated in 10 meetings and gave a speech at the company's annual meeting.

The papers filed by Williams indicate that his work for Arthur Andersen continued through December, after Williams had been elected mayor. That month alone, he was paid $10,000 for two appointments, including a telephone call with Goldstein on Dec. 15 and a Christmas Eve dinner meeting with him.

Williams, who as chief financial officer had authorized 45 contracts with Arthur Andersen worth $4 million, has described Goldstein as a friend.

The NationsBank contract does not specifically detail Williams's work. The bank initially said Williams's contract was for $12,000, but the contract shows it was for $10,000, or $2,000 a month from August through December. The contract required Williams to attend one luncheon meeting with bank officials, and he did not have to submit any written reports.

Staff writer Avram Goldstein and research editor Margot Williams contributed to this report.

CAPTION: Mayor Williams's activities are being reviewed for possible conflicts.