By Lucia Mutikani

WASHINGTON (Reuters) - The number of Americans filing new claims for unemployment benefits fell for a third straight week last week, dropping back to their pre-superstorm Sandy range.

Initial claims for state unemployment benefits dropped 25,000 to a seasonally adjusted 370,000 in the week ended December 1, the Labor Department said on Thursday.

Last week's drop brought them back to their pre-storm's 360,000-370,000 range, which economists said suggested there had been no marked weakening in the labor market. They had forecast claims falling to 380,0000.

"We could reasonably assume there is no underlying deterioration or acceleration in the labor market before the storm," said Pierre Ellis, senior global economist at Decision Economics Inc. in New York.

"We should still have a relative poor payroll reading tomorrow, but we should have some confidence that payrolls would bounce back in December."

The four-week moving average for new claims, a better measure of labor market trends, rose 2,250 to 408,000, reflecting the impact of the late October storm. That was the highest level since October last year.

Last week's claims data has no bearing on Friday's employment report. Economists estimate the monster storm, which slammed into the densely populated East Coast, could subtract between 25,000 and 75,000 jobs from November's nonfarm payrolls.

The closely watched report is expected to show payrolls increased only 93,000 last month after advancing 171,000 job in October, according to Reuters survey of economists. The unemployment rate is seen holding steady at 7.9 percent.

A Labor Department official said there was nothing unusual in the state-level data, but noted claims tend to post their largest percentage increase in the last week of November, catching up from the Thanksgiving holiday.

In addition, seasonal layoffs in sectors like construction, start picking up this time of the year. This will make claims a less useful gauge of labor market conditions in the weeks ahead.

A separate report from consultants Challenger, Gray & Christmas showed planned layoffs at U.S. firms rose nearly 20 percent in November to their highest level in six months.

The claims report showed the number of people still receiving benefits under regular state programs after an initial week of aid dropped 100,000 to 3.21 million in the week ended November 24.

(Reporting By Lucia Mutikani; Editing by Neil Stempleman)