WASHINGTON (Reuters) - The number of U.S. workers applying for unemployment benefits soared by 38,000 last week, posting the highest reading since September 2005 and reinforcing fears that the U.S. economy has stalled, government data on Thursday showed.

A Labor Department official said there were no special factors to explain the increase in initial claims to 407,000 in the week ended March 29, but he said seasonal adjustments to the data owing to the early timing of the Easter public holiday this year may have influenced the reading.

“Part of what is going on is seasonal adjustments and part of it is higher claims,” said the Labor official.

U.S. government Treasury notes extended gains on the news, with investors betting this will encourage the U.S. Federal Reserve to cut interest rates further, while the dollar edged back from earlier highs and stock futures dropped.

“The trend is for rising unemployment. There’s no doubt about it,” said Joe Saluzzi, co-manager of trading at Themis Trading in Chatham, New Jersey. “I’ve been bearish for a long time and I don’t think we have found a bottom.”

Economists polled by Reuters had expected initial jobless claims to increase to 370,000 in the week ending March 29, compared with 369,000 the prior week, initially estimated at 366,000 claims.

The four-week moving average of new claims, a more reliable guide to underlying labor market trends because it smoothes out weekly data swings, also increased sharply. It rose to 374,500, which was the highest reading since October 2005.

Analysts fear a housing slump and credit crunch may have tipped the U.S. economy into recession and are scrutinizing the labor market for evidence of slackening jobs that could chill consumer spending.

Economists polled by Reuters had expected initial jobless claims to increase to 370,000 in the week ending March 29, compared with 369,000 the prior week, initially estimated at 366,000 claims.

The four-week moving average of new claims, a more reliable guide to underlying labor market trends because it smoothes out weekly data swings, also increased sharply. It rose to 374,500, which was the highest reading since October 2005.

Analysts fear a housing slump and credit crunch may have tipped the U.S. economy into recession and are scrutinizing the labor market for evidence of slackening jobs that could chill consumer spending.

In further evidence of soft labor conditions. the number of workers remaining on jobless benefits climbed 97,000 to 2.94 million in the week ending March 22, the most recent week these figures were available. This compared with forecasts for 2.87 million so-called continued claims.

It was the highest reading for continued claims since July 2004.

The weekly jobs data was released on the eve of the monthly payrolls report on Friday, but was collected in a week that falls after the survey period for the monthly update. Analysts are expecting the U.S. economy shed 60,000 jobs in March after losing 63,000 the month before.

Federal Reserve Chairman Ben Bernanke warned on Wednesday that unemployment would push up as the U.S. economy slowed in the first half of the year.

The Fed has slashed interest rates 3 percentage points since mid-September to shield the economy from the housing slump and investors think it will cut again at its next scheduled policy meeting, at the end of this month.