(Reuters) - U.S. consumer spending got off to a fairly firm start in the third quarter, rising by the most in five months and offering hope economic growth could pick up this quarter.

Other data on Thursday showed the number of Americans filing new claims for jobless benefits was unchanged last week, indicating a lack of strong improvement in the labor market and keeping additional monetary stimulus from the Federal Reserve on the table.

The Commerce Department said consumer spending increased 0.4 percent after a flat reading in June. Last month's rise in consumption, which accounts for 70 percent of U.S. economic activity, was in line with economists' expectations.

When adjusted for inflation, consumer spending increased 0.4 percent, also the largest increase since February.

"The improvement in spending activity suggests that overall economic activity may be off to a fairly decent start in the third quarter," said Millan Mulraine, senior macro strategist at TD Securities in New York.

A second report from the Labor Department showed first-time applications for state unemployment benefits were unchanged at 374,000. The four-week moving average for new claims, a better measure of labor market trends, rose 1,500 to 370,250. Jobless claims have risen by 10,000 in August, suggesting some moderation in the pace of job growth this month after payrolls increased 163,000 in July from 64,000 in June.

Even though data on consumer spending and housing suggest that economic activity picked up early in the third quarter, the state of the labor market could determine whether the Fed offers additional monetary stimulus to the economy at its September 12-13 policy meeting.

The unemployment rate, which ticked up to 8.3 percent in July, has been stuck above 8 percent for more than three years, the first time this has happened since the Great Depression.

In addition, business spending is weakening and inflation is slowing.

"Today's data...are not strong enough to prevent the Fed from launching QE3 in mid-September," said Paul Dales, a senior economist at Capital Economics.