A job applicant attends a job fair in Washington, Jan. 8, 2016. REUTERS/Gary Cameron

The number of Americans filing for unemployment benefits unexpectedly rose last week, but the underlying trend continued to point to a strengthening labor market.

Initial claims for state unemployment benefits increased 6,000 to a seasonally adjusted 278,000 for the week ended Feb. 27, the Labor Department said on Thursday. The prior week's claims were unrevised.

Economists polled by Reuters had forecast claims slipping to 271,000 in the latest week. A Labor Department analyst said there were no special factors influencing last week's claims data and only claims for Oklahoma had been estimated.

Claims have now been below the 300,000 threshold, which is associated with healthy labor market conditions, for 52 straight weeks. That is the longest period since the early 1970s.

The four-week moving average of claims, considered a better measure of labor market trends as it irons out week-to-week volatility, fell 1,750 to 270,250 last week, the lowest level since late November.

While the claims data has no bearing on Friday's employment report for February as it falls outside the survey period, it was the latest indication that the labor market remains on solid footing despite a recent tightening in financial market conditions sparked by worries of a recession.

A report on Wednesday showed strong private sector hiring last month, suggesting a pick-up in overall job growth.

According to a Reuters survey of economists, nonfarm payrolls likely increased by 190,000 jobs last month after rising 151,000 in January. The unemployment rate is seen steady at an eight-year low of 4.9 percent.

The claims report showed the number of people still receiving benefits after an initial week of aid rose 3,000 to 2.26 million in the week ended Feb. 20. The four-week average of the so-called continuing claims slipped 750 to 2.26 million.