WASHINGTON - US job openings increased in December 2011, a positive sign of improving job market, the Labor Department reported on Tuesday.

The number of job openings in December was 3.4 million, up from 3.1 million in November 2011, the report said. Although the number of job openings remained below the 4.4. million level when the recession began in December 2007, the job openings rate has trended upward since the end of the recession in June 2009.

The US unemployment rate edged down to 8.3 percent last month from 8.5 percent in December 2011, a near three-year low since February 2009, the Labor Department reported last Friday. But some economists argued that the country still needs stronger growth to put more people back to work.