A consultant's draft report warning the National Highway Traffic Safety Administration that government regulations could force both Chrysler Corp. and American Motors Corp. out of business is fraught with "unattributed statements and unsupported conclusions," the federal agency charged yesterday.

The report, which was commissioned by NHRSA, still is being worked on by Harbridge House Inc., a Boston-based research firm that is being paid $439,00 for its work. The firm submitted the winning bid to study the economic impact of federal auto regulation on the industry.

"Contrary to normal practice," a preliminary draft of the report was sent to various industry officials by Harbridge House before the government had reviewed its contents, NHSTA said.

Copies of the draft report were leaked to newspapers in Detroit during the holiday weekend. The leaked documents appeared ot confirm auto industry opinion that government regulation was imposing a severe strain on the less stable auto makers.

But NHTSA said yesterday that several members of its staff have had a chance to review the document, and "these reviews have raised serious questions about the validity of the report and its conclusions."

NHTSA Administrator Joan Claybrook said Harbridge House is preparing a revised draft based on specific recommendations from the agency.

Claybrook called the release of the incomplete report "most unfortunate."

"We gave a contractor the responsibility for trying to think through a complex problem," she said. "But what they did was find out what industry thought and tell us that."

While Claybrook said that although it is "valuable to know the perspectives of industry," that was not the point of the study. She was extremely critical of the fact that Hartbridge House had spoken to few, if any, consumer advocates or nonindustry sources.

"We will not let any more think-tank studies go along these lines," she added.

Claybrook said the report offered "virtually no substantiation for its findings" and that the accompanying executive analysis provided by Harbridge House "was not even supported by the information in the report."

The Harbridge House draft had contended that Chrysler and AMC are losing even more market share to industry leaders Ford Motor Co. and General Motors Corp. because of increased costs of government regulation, which the smaller firms have more difficulty financing.

The report warned that the problems could worsen should the country be hit by a recession.

But NHTSA, which had commissioned the report to help in the drafting of another report it must make to Congress Jan. 15 concerning the state of the fuel economy program, disagreed sharply with the Harbridge analysis.

In a written critique of the Harbridge House draft, NHTSA's Barry Felrice said, "I find HH's efforts of little use to NHTSA . . . HH has done little analysis . . . "

Felrice pointed out several examples of what he called "weak analysis" in the report, including an HH projection that Ford would spend $1.9 billion per year to meet new regulations, "while Ford itself has placed this figure at a maximum of $1 billion per year."

A spokesman for the Boston research firm defended the study, and said that the final version will not contain major changes from the early draft. NHTSA expects formal presentation of the completed report next month.