The number of workers filing new applications for unemployment insurance unexpectedly rose last week for the first time since early April, government data showed on Thursday, dealing a blow to the labor market recovery.

Initial claims for state unemployment benefits increased 25,000 to a seasonally adjusted 471,000 in the week ended May 15, the highest level since the week ended April 10, the Labor Department said.

Analysts polled by Reuters had expected claims to fall to 440,000 from the previously reported 444,000, which was revised marginally up to 446,000 in Thursday's report.

The four-week moving average of new claims, which is considered a better measure of underlying labor market trends, rose 3,000 to 453,500.

A Labor Department official said there was nothing unusual in the state level data. The claims data fell in the survey week for the government's closely watched employment report for May. That report will be released on June 4.

New applications for unemployment benefits had been grinding lower even though payrolls have now grown for four straight months. Analysts believe the elevated level of initial claims indicates the unemployment rate will remain high for a while and only come down gradually as small businesses are still struggling.

The jobless rate edged up to 9.9 percent in April from 9.7 percent in March.

The number of people still receiving benefits after an initial week of aid fell 40,000 to 4.63 million in the week ended May 8, the Labor Department said. The level was above market expectations for 4.60 million, but was the lowest since late March.

The insured unemployment rate, which measures the percentage of the insured labor force that is jobless, was unchanged at 3.6 percent in the week ended May 8. It was the fifth straight week that the rate was unchanged at that level.

(Reporting by Lucia Mutikani; Editing by Andrea Ricci)