A bill to require the nation's employers to provide health insurance to workers was approved, 10 to 6, by the Senate Labor and Human Resources Committee yesterday. Business groups vowed an all-out effort to defeat the bill when it reaches the Senate floor.

"The health issue is on the national agenda," committee Chairman Edward M. Kennedy (D-Mass.) said after the vote, adding that he is determined to push for Senate floor passage this year despite the opposition. Spokesmen for small businesses said the bill's cost could force many firms to cut their work forces and could threaten their survival.

If enacted, the measure would bring about the largest expansion of health care coverage since Medicare and Medicaid were passed in 1965.

Employers would be required to provide workers employed 17.5 hours weekly or more with a minimum package of benefits including all necessary hospital care, physician care, diagnostic and screening tests, limited mental health benefits and prenatal and well-baby care, plus a "catastrophic" cap on out-of-pocket expenses of $3,000 a year.

Workers could be required to pay up to 20 percent of the premiums, except for low-income workers. Kennedy estimated the cost to an employer at about $1,045 a year for a full-time worker.

Before reporting the bill to the floor, the committee approved by voice vote an amendment by Sens. Tom Harkin (D-Iowa) and Howard M. Metzenbaum (D-Ohio) postponing coverage for five years for about 5 million workers employed by small businesses with five or fewer employees.

The amendment was designed to allay small business fears, but Sen. Lowell P. Weicker Jr. (Conn.), the only Republican who voted for the bill, said, "This bill is going to be opposed by every one of the groups representing small business . . . . They don't want any bill. Period. Over and out."

In a sharp attack, Sen. Orrin G. Hatch (R-Utah) called the bill "socialism pure and simple." Hatch said "this one hurts workers" and said estimates of the bill's costs range "anywhere from $28 billion to $100 billion" a year and estimates of the number of jobs that would be eliminated range from 100,000 to 1 million.

"We don't have the guts to stand up and say tax the American people directly" to pay for the coverage, Hatch said; instead "we mandate" that employers provide benefits at their expense, he said.

Kennedy noted that "more than 37 million Americans have no health insurance at all . . . and millions more have insurance that is inadequate by any reasonable standard."

He said that about 22 million of the 37 million uninsured would be provided with coverage by the bill after the five-year phase-in. Household workers would not be covered and some employees of small family farms would be exempt for a time.

Kennedy said the Congressional Budget Office estimated gross costs at $27.1 billion a year and said that four groups of specialists had estimated job losses due to the bill at zero to no more than 100,000.

Kennedy said the real cost of the bill would be about $15 billion, not $27.1 billion, because hospitals, small businesses and individuals would save the $12 billion they spend on free care to uninsured persons, on extra administrative costs and on premiums for a variety of policies the bill would replace.

The bill has drawn the support of a coalition of organized labor, some large corporations and welfare groups. Reps. Henry A. Waxman (D-Calif.), Augustus F. Hawkins (D-Calif.), William L. Clay (D-Mo.) and Austin J. Murphy (D-Pa.) are sponsoring the House version.