First-time claims for US unemployment benefits fell last week, adding to signs of a firming jobs market, government data showed Thursday. Initial jobless claims, a sign of the pace of layoffs, totaled 311,000 in the week to March 22, down from 321,000 the previous week, the Labor Department said. The four-week moving average fell by 9,500 to 317,750 claims. A year ago the average stood at 343,000 claims. Ian Shepherdson of Pantheon Macroeconomics warned not to conclude that the recent fall in claims is a permanent shift. "We are still cautious about calling the data evidence of a real downshift in the trend," he said. "Claims are volatile and it takes more than three good weeks to establish a new trend." In February, the US unemployment rate was 6.7 percent and the economy added 175,000 jobs, picking up the pace of job growth.