NEW YORK — Don't tell Betty Deal age discrimination is illegal.

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She's well aware of the laws protecting older employees in the work place, but she also knows what it's like to be middle-aged and suddenly thrust into a fiercely competitive labor market after a corporate downsizing.

"When you go in and talk to [job interviewers], they ask you, 'How long do you think you'll be with us?' or 'Are you going to retire?'

"Then they'll say something like, 'We were looking for someone with a little less experience.' What they really meant to say is they want someone younger," said Deal, 56, of San Jose, Calif., who lost her $60,000-a-year management job with a Silicon Valley electronics firm four years ago.

She has yet to find permanent, full-time work.

Stable jobs are becoming even scarcer nationwide as mega-mergers in the banking and entertainment industries and corporate restructurings among behemoths like AT&T, Colgate-Palmolive and Merck bring about thousands of layoffs.

All ages are at risk. However, unemployment for the 50-plus crowd, many of whom are in the twilight years of their careers and at peak earnings, poses special problems in a decade of corporate cost-trimming and downsizing.

Some senior workers will be offered early retirement, but even those receiving benefits may still need to keep working to make ends meet. Many career counselors have reported a recent rise in the number of older clients.

Unfortunately, "companies are more likely to hire part-timers . . . temporaries . . . or younger people with less experience," said William S. Payson, who runs the Senior Staff Job Information Exchange in San Jose, which helps match older job seekers with available jobs. "The companies like the flexibility; it enables them to expand and contract their labor force without creating headlines."

Jim Robinson Jr., 52, of Portland, Ore., has seen that strategy firsthand. Before being laid off in the summer of 1992, Robinson earned around $95,000 a year as a systems engineering manager for International Business Machines. While his two-page resume displays a lifetime of achievements--including 25 years of steady movement up IBM's corporate ladder--he has yet to find a comparable position.

"I think it has to do with my salary. Most employers, I've discovered, do not wish to pay more than $60,000 to $70,000 for an employee. Period," Robinson said. "There's the six-digit money in the executive suite, but you have to have entry to the executive suite before your 45th birthday.