U.S. workers put in more hours on the job last year than the labor force of any other industrial nation, outpacing employees in Canada, France, Germany, Japan and the United Kingdom, a study by a U.N. agency finds.

The average American worked 1,978 hours in 2000, compared with 1,942 hours in 1990, according to Jeff Johnson, the economist who headed the study by the International Labor Organization.

That comes to almost an additional 40-hour work week.

"The increase in the number of hours worked within the United States runs counter to the trend in other industrialized nations where we see declining annual hours worked," Johnson said.

Japan held the title for the most hours worked until the mid-1990s, when the United States surged ahead. Now, Americans work almost a month more than the Japanese and almost three months more than Germans.

Economists have said Americans are working more because of the economic boom of the 1990s and an increase in young workers looking to make a good impression.

Only workers in South Korea and the Czech Republic outworked Americans, though neither nation is considered industrial by the United Nations.

South Koreans put in almost 500 more hours than U.S. workers; the labor force of the Czech Republic clocked in 100 hours more.