CHICAGO — It sounds like an oxymoron, but the concept of working in retirement is fast becoming the norm for many older Americans — forced by dwindling financial resources and a recessionary economy to stay in or return to the job market.

Longer lifespans and a desire to remain productive and connected already had begun pushing the number of older workers higher. Now the financial crisis is accelerating interest in working later, with career sites and organizations for seniors and older workers reporting a surge in job-hunting efforts.

Marian Austin, 63, of Alfred, Maine, is among those who need to work again just to make ends meet in retirement. In this economy, her late ex-husband's Social Security isn't nearly enough.

"It's been difficult," said the former gift shop owner and retail manager, who retired two years ago. "I don't know how I will pay for fuel oil for heating. I can't walk into a grocery store and buy what I want. I don't look forward to Christmas because I can't buy gifts this year."

AARP, the nation's largest advocacy group for older Americans, saw dramatic evidence of the trend in September when more than 2,000 people attended its annual job fair in Washington, D.C., more than double the previous year's attendance. The job-seekers included many who had been recently laid off and retirees worried about the economy and the pressure on their limited resources.

"We've definitely seen an increase in the sense of urgency in terms of jobs," said Deborah Russell, the organization's director of work force issues.

A market for retirement jobs essentially emerged a decade or so ago. Now postings for those at or approaching retirement age are an important and growing phenomenon in the labor market, as evidenced by online job boards that include www.RetirementJobs.com, www.RetireeWorkforce.com and www.Seniors4Hire.org, which cater to not just retirees but anyone 50 and older.

Demand for such resources is only likely to grow with the graying of the workforce expected to continue. Workers age 65 and over are expected to account for 6.1 percent of the labor force by 2016, up sharply from 3.6 percent in 2006, according to the U.S. Bureau of Labor Statistics.

"For decades we've been making it easier for people to get out of the labor market," said Marc Freedman, CEO of Civic Ventures, which focuses on helping older baby boomers launch second careers involving social contribution. "Now there's a growing need in the opposite direction."

Despite the increased opportunities, seniors may find the job market for them is as tight as for everyone else in a tight economy.

Going back to work part-time should help Austin get by, but getting hired for a worthwhile job in retail, merchandising or working with disabled people is proving tough. She wonders if age discrimination is a factor.

"A lot of these folks who are hiring are in their 20s or 30s and they think people in their 60s are ancient," she said. "If it comes down between you, with a lot of experience, and a younger person, I feel they're going to go with the younger person."

One concern is that, despite their strengths, older workers often are perceived to resist training, dislike answering to younger bosses or have poor computer training, according to AARP's Russell. Seniors need to assess their skills and seek out job-searching tips, particularly if they haven't gone through the process in recent years, she said.

"The job market has changed," Russell said. "Employers are accepting job applications online, they expect to see your resume online, interviewing has changed, so it's important to keep up."