A former chief regulator of the thrift industry told the Senate ethics committee yesterday that he regarded the intervention of Sen. Alan Cranston (D-Calif.) on behalf of Charles H. Keating Jr.'s Lincoln Savings and Loan Association as "unusual," although he did not see it as improper at the time.

The testimony by M. Danny Wall, former chairman of the Federal Home Loan Bank Board, touched off a heated exchange between committee counsel Robert S. Bennett and Cranston's attorney over an affidavit in which Wall appeared to have changed his conclusions about the propriety of Cranston's conduct.

Had he known then that voter registration groups associated with Cranston were receiving large contributions from Keating's companies at the same time that Cranston was calling him, "I would have been very disturbed by Senator Cranston's calls to me regarding Lincoln," Wall said in the Nov. 7 affidavit.

Cranston and four other senators -- Dennis DeConcini (D-Ariz.), John Glenn (D-Ohio), John McCain (R-Ariz.) and Donald W. Riegle Jr. (D-Mich.) -- are under investigation to determine the propriety of their intervention for Keating during a time when he was contributing more than $1.3 million to their campaigns and causes.

In the affidavit, Wall said he received "numerous" phone calls from Cranston about the examination of Lincoln by regulators and later urging prompt consideration of proposals for purchase of the failing thrift before it was seized by the government in April 1989. Wall said he also received several calls from DeConcini about the sale.

"Based on my experience as chairman of the Bank Board, I would say that it was unusual for a senator to place so many phone calls to me with regard to a single savings and loan institution," he said in the affidavit, speaking of Cranston.

"With the benefit of other facts now coming to light, it is apparent to me that Senator Cranston got substantially involved in the affairs of Lincoln," and the "breadth and depth" of that involvement was unusual, he said.

"At the time I had these conversations with Senator Cranston, I did not believe there was anything improper about them and so testified before the House Banking Committee" a year ago, he said.

"However, I was not aware at the time these calls were made, or at the time that I testified, that the large contributions made by Mr. Keating's companies to voter registration groups closely affiliated with Senator Cranston appear to have coincided with several of Senator Cranston's calls to me regarding Lincoln," he said.

"Had I known at the time that the communications to me from Senator Cranston were contemporaneous with these substantial contributions from Mr. Keating, I would have been very disturbed by Senator Cranston's calls regarding Lincoln. . . . I probably would have reacted differently to Senator Cranston's numerous contacts on behalf of Lincoln," he added.

Keating's contributions to Cranston totaled nearly $1 million, including $850,000 for voter registration groups that he sponsored.

Bennett asked Wall about his conclusions near the end of nearly five hours of testimony yesterday, prompting Cranston attorney William W. Taylor III to protest that he was doing so to avoid cross-examination and thus have the last word on the issue. A clearly irritated Bennett broke off his questioning, but ethics committee Vice Chairman Warren B. Rudman (R-N.H.) intervened and asked Wall a brief question about his view of Cranston's intervention.

During earlier questioning by committee member David Pryor (D-Ark.), Wall said none of the senators ever asked him to relax regulations, approve a specific sale or slow enforcement of rules affecting Lincoln. But he qualified his answer when Pryor asked if he believed at the time that they may have violated standards dealing with the "appearance" of propriety, saying, "Nothing I felt at the time."

Wall, staff director of the Senate Banking Committee before he became a regulator, also said lawmakers rarely or only in a "very limited" way intercede on behalf of a constituent when they know a criminal investigation of the case has been recommended. The five senators learned that thrift regulators were proposing such a probe at a meeting with the regulators in April 1987, and Cranston's and DeConcini's intervention continued beyond that point.

DeConcini, meanwhile, sharply attacked Edwin J. Gray, the former regulator who testified last week that the senator had "crossed the line" ethically in the 1987 meetings with regulators on Keating's behalf.

Denying the charge and calling Gray "a most incompetent regulator," DeConcini said: "He doesn't like the fact that he was in charge when all of this happened, and that he wasn't man enough to sit down and talk to four senators and put it off to his regulators in San Francisco. It's a disaster that Mr. Gray brought about in this industry and it's most unfortunate."