The number of planned layoffs at U.S. companies dropped for a third straight month in August and hit a 20-month low, a report showed on Thursday.

Employers announced 32,239 planned job cuts last month, down 12.5 percent from 36,855 in July, according to the report from consultants Challenger, Gray & Christmas Inc.

It was the fewest number of planned cuts since December, 2010, but the consultancy said the August decline "may be further evidence of an improving economy or it may simply be a summer lull in job-cut activity."

The report came a day before the U.S. government is set to release the key August jobs report, for which economists expect payrolls to have dipped from July. The jobless rate was high at 8.3 percent in July, causing deep concern at the Federal Reserve, which aims for maximum U.S. employment.

Challenger said the planned cuts in August were 37 percent lower than a year earlier. So far this year, employers have announced 352,185 cuts, down slightly from the 363,334 in the first eight months of last year.

"Job cuts slowed significantly over the summer, but it is too early to determine whether this is a trend," John Challenger, chief executive of the consultancy, said in a statement. "If international job-cut activity is any indication, we may see a surge in downsizing in the final months of 2012 and into 2013."

Historically, the heaviest job cuts are in the fourth quarter.

In August, cuts were deepest in the telecommunications sector, where employers announced 4,584 layoffs, Challenger said. Most of these were the anticipated cuts resulting from Google Inc's acquisition of Motorola Mobility. 

(Reporting by Jonathan Spicer; Editing by Chizu Nomiyama)