NEW YORK (CNN/Money) - Workers in the United States are far more nervous about losing their jobs than they were six months ago and are now among the least confident employees among the world's leading economies, according to a recent survey.

Right Management Consulting, which conducts surveys in 18 nations around the globe, found in its September and October survey that 23.8 percent of U.S. workers said it was very possible or somewhat possible that they would lose their jobs in the next 12 months. That's up from only 19.3 percent who were that concerned about job loss in the survey conducted six months ago.

Just less than half of U.S. workers surveyed said it was not at all possible they would lose their jobs, down from 52 percent who were that confident six months ago.

Brian Clapp, senior vice president for Right Management, said that the economic upheaval in the wake of Hurricane Katrina was probably a factor in the growing concerns of U.S. workers.

"My general sense is there's more cause for uncertainty and worry than there is for stability and optimism right now," he said.

While Americans are feeling less secure in the most recent reading, overall the survey found employee confidence improving in 13 of the 18 economies where the survey was conducted.

The percentage of U.S. workers concerned about losing their job is close to the highest level seen worldwide. It only marginally trails the 24.2 percent of those surveyed in the United Kingdom and 24 percent in Canada who share that fear.

But the U.S. workers are more concerned than their British or Canadian counterparts with being able to replace their current jobs should they lose it. Asked how easy it would be for the average person who is laid off to find a similar job at the same pay, 80.2 percent of Americans surveyed said it would be somewhat or very difficult. That's little changed from the 79.8 percent who had that concern six months ago.

Workers in five European nations -- Germany, France, Switzerland, Italy and the Netherlands -- are the only ones who think it would be tougher to replace a job. The Germans are most concerned, with 95.5 percent believing it would be very or somewhat tough to replace a job.

The combination of the two questions puts the U.S. workers surveyed near the bottom of the firm's Career Confidence Index, ahead of only Switzerland and Germany. Six months ago the United States was near the worldwide average, with seven nations having less confident workers.

In both surveys, Norway had the most confident workers, with only 3.1 percent saying it was very or somewhat possible they would lose their jobs in the next 12 months, while nearly three in four said it was not at all possible.

Just over 1,000 Americans participated in the survey, and the other nations had 300 to 600 workers surveyed. Right Management is a wholly owned subsidiary of Manpower (Research), the U.S. based provider of temporary employees.

For more on the state of the job market and what it means for you, click here.