WASHINGTON -- U.S. employers advertised more job openings in January, suggesting that hiring will remain healthy in coming months.

Job openings rose 2.2 per cent in January from December to 3.69 million, the Labor Department said Tuesday. Openings had fallen nearly 5 per cent in December, and they remain below November's level of nearly 3.8 million.

Yet the report provided further evidence that the U.S. job market is strengthening. Employers laid off the fewest workers in January than in any month since records began in 2001. And the number of Americans who quit their jobs rose to the highest in more than four years. People usually quit when they have another job, so more quitting suggests it is easier to find work.

The biggest increase in job openings was in professional and business services, which includes high-paying fields such as accounting, engineering, and architecture. It also includes temp jobs, which typically carry few benefits. The next-largest gain was in retail.

On Friday, the government reported that hiring in February was robust: Employers added 236,000 jobs, and the unemployment rate fell from 7.9 per cent in January to a four-year low of 7.7 per cent. February capped a fourth-month hiring spree in which employers added an average of 205,000 jobs a month.

At the same time, the competition for open positions remains strong. About 12.3 million people were unemployed in January, which means there were 3.3 unemployed people, on average, competing for each job. That's sharply down from a peak of nearly 7 unemployed people competing for each job in July 2009. But in a healthy economy, the ratio is roughly 2 to 1.

The report, known as the Job Openings and Labor Turnover survey, or JOLTS, calculates total hiring, layoffs and quits. By contrast, the department's monthly jobs report measures the unemployment rate and net hiring. Net hiring equals total hiring minus layoffs, quits and other separations.

Since the recession ended in June 2009, total hiring hasn't increased as fast as job openings have. Businesses have been still slow to fill vacancies.

The number of openings has increased 55 per cent. The 3.69 million openings in January is only slightly less than the nearly 4 million that were posted each month, on average, before the recession.

Total hiring, though, has risen only 17 per cent in the same period. It rose to 4.25 million last month. That's well below the pre-recession monthly average of about 5.1 million.

Still, because employers are laying off fewer workers, net hiring has accelerated in recent months -- a sign that employers are confident about their prospects and haven't been discouraged by tax increases or higher gas prices.

Monthly job gains averaged more than 200,000 from November through February. That compares with an average of 154,000 jobs from July through October and only 108,000 from April through June.

Other reports also suggest that steady hiring will continue. The ManpowerGroup said Tuesday that its latest quarterly survey of 18,000 U.S. employers found that 18 per cent expect to add jobs in the April-June quarter. That's up one percentage point from the previous quarter. Only 5 per cent say they will cut jobs, 3 points lower than in the previous quarter.

Strong auto sales and a steady housing recovery are spurring more hiring, which could trigger more consumer spending and lead to stronger economic growth. Auto sales rose in January and February after reaching a five-year high in 2012.

A big source of strength has been home sales and residential construction: New-home sales jumped 16 per cent in January to the highest level since July 2008. And builders started work on the most homes last year since 2008.