The number of Americans initially applying for unemployment aid continued to decline last week, hitting the lowest level in four years, the U.S. Labor Department reported Thursday.

The department said the advance figure of seasonally adjusted initial claims for jobless benefits was 355,000 in the week ending March 31, a drop of 6,000 from the previous week's revised figure.

The fresh figure was the lowest since April 2008. The number of jobless claims below 375,000 indicated a sustained drop in the unemployment rate.

Economists believe that the downward trend in applications is another positive sign for labor market recovery, saying that job gains will also be strong in March.

Meanwhile, the four-week moving average, which helps smooth out week-to-week volatility, edged down by 4,250 to 361,750.

The advance figure for seasonally adjusted insured unemployment during the week ending March 24 was 3.338 million, a 16,000 drop from one week earlier.

Although the U.S. businesses added an average of 200,000 net jobs per month in the past six months, the job market has a long way to go before it fully recovers from the recession, as the current 8.3 percent unemployment is still painfully high.