WASHINGTON, Dec 24 (Reuters) - The number of Americans filing new claims for unemployment benefits unexpectedly fell last week, underscoring the economy's enduring strength.Initial claims for state unemployment benefits dropped 9,000 to a seasonally adjusted 280,000 for the week ended Dec. 20, the Labor Department said on Wednesday. It was the fourth straight week of declines in claims.The report came a day after the government reported the economy expanded at its fastest pace in 11 years in the third quarter and consumer spending increased solidly in November.Economists polled by Reuters had forecast claims ticking up to 290,000 last week. The prior week's data was unrevised. The four-week moving average of claims, considered a better measure of labor market trends as it irons out week-to-week volatility, fell 8,500 to 290,250 last week.The Federal Reserve last week gave the economy a vote of confidence, lowering its unemployment rate forecast and signaling it could start raising interest rates in mid-2015.A Labor Department analyst said there were no special factors influencing last week's claims data. The report showed the number of people still receiving benefits after an initial week of aid rose 25,000 to 2.40 million in the week ended Dec. 13.The so-called continuing claims data covered the week during which the government surveys households to compile the unemployment rate for December.Continuing claims rose by 80,000 between the November and December survey periods, suggesting the jobless rate probably held at a six-year low of 5.8 percent.(Reporting by Lucia Mutikani; Editing by Andrea Ricci)Join the conversation about this story Click here to read full news..