Wal-Mart Stores Inc. said Monday it will relax eligibility requirements for part-time employees who want health insurance, allowing an additional 150,000 workers to gain coverage if they choose.

Until now, the employees have had to work for Wal-Mart for two years to qualify for employer-sponsored insurance. Beginning next month, they will have to work at the company for one year. The coverage also will extend to their children.

The changes were announced by one of the company's vice presidents, Susan Chambers, at a meeting of business and health care executives.

Wal-Mart has been strongly criticized by unions and others for providing what they describe as inadequate health benefits. However, Chambers said Wal-Mart's health insurance costs have risen at a rate of 19 percent annually over the past three years.

''Keep in mind that covering part-time employees is not the norm in retail,'' Chambers said. ''But every American deserves health care, and we want to lead by taking these steps. We hope that others in the retail community will work with us to do the same.''

Chambers did not provide details about how much the change would cost the company. She said it's now picking up about 70 percent of the costs for each employee's health care, and she expects that percentage to increase.

Unions contend the company's benefits are too stingy, forcing taxpayers to pick up more of the cost as the workers lacking coverage turn to the government.

''This is what's so cruel: They're basically expanding health care coverage to workers who can't afford it because their pay is so poor and the health care deductibles and premiums are so high,'' said Chris Kofinis, spokesman for WakeUpWalMart.com, a group funded by the United Food and Commercial Workers union.

Chambers said the version of the health plan that the company expected most employees to sign up for would be available for $23 a month. Workers' children would be included for $15 more, whatever the size of the family.

But Kofinis countered that the coverage also calls for a deductible that requires the worker to pick up the first $1,000 in medical expenses, and the deductible rises to a maximum of $3,000 for families. He said many workers just can't afford that amount, and will pass on the new coverage.

There are some exceptions to the deductible. Namely, workers can visit a doctor up to three times in a year, and they can get three prescriptions filled with a $20 copay before they have to start meeting the deductible, a public relations staffer working with Chambers noted.

Wal-Mart's latest announcement on health care coverage is the third time in less than a year that it has moved to improve health benefits. The announcements reflect growing outside pressure on the company, which was exhibited in the state of Maryland recently. There, the state's legislature passed a law that requires companies with more than 10,000 Maryland employees to spend at least 8 percent of their payroll on employee health care or pay the difference into the state's Medicaid fund.

Chambers also told fellow business executives that the company would expand in January the list of generic drugs available at $3 a prescription. It would enhance contributions to health savings accounts, and it would provide workers with a 10 percent discount on fresh fruits, vegetables and other healthy foods.