A former top official of the Federal Home Loan Bank Board, which regulates savings and loan associations, violated federal conflict-of-interest laws by signing documents that affected a thrift for which he once worked, a congressional oversight committee said yesterday.

The allegation involves Norman H. Raiden, who resigned in December as the bank board's chief counsel, and was stated in a letter to the bank board from Rep. John Dingell (R-Mich.), chairman of the oversight subcommittee of the House Energy and Commerce Committee.

The letter, addressed to Bank Board Chairman Edwin J. Gray, is the latest salvo in a war of words between the subcommittee and the bank board.

"My review of the subcommittee's record confirms my original views from questioning Mr. Raiden that his conduct at the bank board involved serious conflicts of interest and the sloppiest of ethical principles," Dingell said in the letter, dated Feb. 10 and received yesterday by the bank board.

Gray said yesterday that he needs time to study the letter before responding.

Since last summer, Dingell's subcommittee has held a series of hearings to examine the collapse in April 1985 of the Beverly Hills Savings and Loan Association as part of a general investigation into the credibility of independent auditors and the oversight capacity of regulatory agencies.

Raiden acknowledged during those hearings that he signed at least nine documents relating to the Beverly Hills thrift, prompting an outcry from Dingell and other congressmen. In response, Gray called for the bank board's inspector general to investigate Raiden's activities.

The documents he signed concerned requests from the thrift to sell securities and take other actions that would affect its balance sheet, including requests to sell $180 million in certificates of deposits.

As an attorney in private practice with the Los Angeles law firm of McKenna, Conner & Cuneo, Raiden for many years was the lead outside lawyer for the Beverly Hills thrift until he left the law firm in 1983 to become chief counsel at the bank board. Two months ago, Raiden left the bank board to rejoin McKenna.

"Now that Mr. Raiden has completed the revolving-door cycle by returning to his former law firm . . . the subcommittee's concerns regarding his participation in matters affecting the McKenna firm and its clients have been proven accurate," Dingell said in the letter yesterday.

Raiden and Gray have insisted that the documents Raiden signed did not involve issues Raiden worked on when he was a lawyer for the Beverly Hills thrift.

In December, Gray wrote Dingell saying that the inspector general's report "concluded that Mr. Raiden did not violate any government ethical standards."

Dingell disagreed yesterday, telling Gray that the inspector general's report "does not provide proof for your assertion that Raiden avoided real or apparent conflicts of interest" regarding the Beverly Hills thrift.

The bank board inspector general, Paul Gibbons, who reports to Gray, said last week that he was a fact-finder only in the Raiden investigation and that any conclusion about wrongdoing was Gray's responsibility.

The Office of Government Ethics, which is an independent unit within the Office of Personnel Management, reviewed and did not contest Gray's conclusion that Raiden had acted ethically, Gibbons said.

Dingell's letter criticized Raiden on other matters, too. "Mr. Raiden's assistant routinely signed Mr. Raiden's name to important documents without notation, without informing Mr. Raiden, and without a written delegation of signature authority," which bank board regulations require, Dingell's letter said.

Raiden repeated yesterday that, as a bank board official, he never violated federal codes barring even the appearance of conflicts or American Bar Association codes stating that "a lawyer serving as a public officer or employe shall not . . . participate in any matter in which the lawyer participated persoanlly and substantially while in private practice . . . "

Raiden said, however, that he would have preferred to have the Office of Government Ethics conduct any investigation and bypass bank board officials altogether. That might have cut short the shouting matches with Dingell on this issue, he said.

The controversy over Raiden is the latest in a series of incidents that have resulted in an investigation of activities of at least two other bank board executives, including Gray.

Two weeks ago, for example, Gray launched an investigation concerning Shannon Ann Fairbanks, who sought bids on a $500,000 home loan using her title as bank board chief of staff. In 1984, the FBI investigated -- and cleared -- Gray on allegations that he improperly used a special entertainment fund and failed to account fully for extensive redecoration of his office.