Five of the nation's top 20 property and casualty insurance companies are financially shaky and might not weather an economic downturn, consumer watchdog Public Citizen said in a study released yesterday.

Without tougher standards and stricter regulation of the industry, there "could be another taxpayer bailout on the model of the savings and loan industry," said Joan Claybrook, president of Public Citizen.

But insurance industry representatives criticized the report -- "Insurance-The Next Industry in Crisis?" -- as misleading and superficial, although one conceded to an insolvency problem.

Sean Mooney, senior vice president of the Insurance Information Institute, a trade association, said: "We don't think the industry is the next savings and loans. ... There is an insolvency problem but not on the same dimensions as the problems in savings and loans."

The study singled out Aetna Casualty Group, American International Group Inc., Hartford Insurance Group, Liberty Mutual Insurance Co. and United States Fidelity and Guaranty Group as the most risk-prone firms.

Caroline Smith DeWaal, the study's author, said it would be disastrous for the state funds that protect policyholders if any of the firms met financial trouble. The report urges the federal government to beef up laws against fraud, insurance regulation and set minimum solvency standards.