The number of planned layoffs at U.S. firms rose to a 16-month high in July as sectors which had been seeing fairly few layoffs unexpectedly bled jobs, a report on Wednesday showed.

Employers announced 66,414 planned job cuts last month, up 60.3 percent from 41,432 in June, according to a report from consultants Challenger, Gray & Christmas, Inc.

July's job cuts also were up from the same time a year ago, rising 59.4 percent from the 41,676 job cuts announced in July 2010, and recording the largest monthly total since March, 2010.

What may be most worrisome about the July surge is that the heaviest layoffs occurred in industries that, until now, have enjoyed relatively low job-cut levels, John A. Challenger, chief executive officer of Challenger, Gray & Christmas, said in a statement.

Layoffs in the pharmaceutical and retail sectors overtook nonprofit and government job cuts last month, accounting for 20.32 percent and 16.93 percent of announcements respectively.

Job cuts at Merck & Co., Borders, Cisco Systems, Lockheed Martin and Boston Scientific accounted for 57 percent of the July total, according to Challenger, making July the first month in seven when the government sector did not shed the most jobs.

A casual observer certainly might conclude that the wheels just fell off the recovery wagon, said Challenger.

Government and nonprofit profit job cuts still account for the largest share of planned layoffs in the first seven months of the year.

For 2011 so far, employers have announced 312,220 cuts, down 8 percent from the first 7 months of 2010.

The rise in job cuts comes two days ahead of the U.S. government's key jobs report on Friday, which is forecast to show the pace of job creation accelerated last month. The economy is expected to have gained 85,000 jobs, not enough to push the unemployment rate below its current 9.2 percent.

(Reporting by Alexandra Alper, Editing by Chizu Nomiyama)