President Clinton will punish health-insurance companies that deny coverage to sick people, in violation of a 1996 law, by excluding them from the lucrative insurance market for federal employees, administration officials said.

The law was intended to make insurance more readily available to millions of Americans who change or lose their jobs. But federal and state officials said Monday they saw worrisome signs that some health-insurance companies were circumventing the law. They said some companies discouraged sales to eligible individuals, charged very high premiums or penalized insurance agents selling coverage to customers with pre-existing medical problems.In a directive being issued Tuesday, Clinton will order the Federal Office of Personnel Management, which negotiates health benefits for federal employees and their dependents, to use its purchasing power to "ensure that health plans come into compliance" with the 1996 law.

The main authors of the health-insurance measure, the Kassebaum-Kennedy law, were Nancy Kassebaum Baker, R-Kan., who retired from the Senate last year, and Sen. Edward Kennedy, D-Mass.

First, Clinton's draft order says, all health plans that insure federal employees will have to certify that they are complying with the Kassebaum-Kennedy law in their private insurance business.

"Specifically," it continues, "I direct OPM to take all appropriate action, up to and including termination of a participating health plan from the Federal Employees Health Benefits Program," if it finds that any insurer is violating the letter and spirit of the law.

The federal employee program is the nation's largest employer-sponsored health-insurance program, covering 9 million people through 350 health plans.

The National Association of Insurance Commissioners has agreed to inform the federal government of any violations found by state officials. Glenn Pomeroy, president of the association, said, "We are pleased to work with the administration in a partnership to make sure that everyone entitled to the protections of the Kassebaum-Kennedy law gets them."

Pomeroy, the insurance commissioner of North Dakota, said state officials would be asked to inform the federal government whenever they imposed fines or other penalties on insurers for violating the standards set in the 1996 law. Most states have written the federal standards into state law.

Clinton intends to have the Federal Health Care Financing Administration, which oversees state regulation of health insurance, tell the Office of Personnel Management about any insurance companies that flout the 1996 law in the states that have not revised their laws. Missouri, California and Rhode Island are among the states that have not revised their laws to conform with federal standards.

Federal and state officials said they could not immediately identify companies that had violated the 1996 law. But state officials said they would probably discover violations when they investigate complaints or conduct routine examinations of insurers' practices.

In a separate action, the White House on Monday announced an effort to help more than 3 million people get assistance in paying Medicare premiums. The assistance is available to elderly and disabled people with low incomes (up to $11,108 a year for an individual and $14,888 for a couple).

Medicare premiums now total $525.60 a year and are expected to increase over the next decade, to $1,268 a year in 2008.