U.S. chief executives' view of the economy was little changed in the fourth quarter, though they are growing concerned about the risk of inflation in raw material prices, according to a survey released on Wednesday.

Of the Business Roundtable CEOs polled, 35 percent said they expected to add jobs in the United States over the next six months, down from 36 percent who expected that in October. Sixty-eight percent expected their companies' sales to rise in the next six months, up from 65 percent last quarter.

The group's quarterly CEO Economic Outlook index inched up to 77.9, from 77.6 in the third quarter. Any number above 50 represents growth. They estimated real U.S. gross domestic product would rise 2 percent next year.

We continue to see strengthened fundamentals in American business but it's combined with an uneven and slow recovery and reflects continued uncertainty by CEOs over the next six months, said James McNerney, CEO of Boeing Co .

The group, which represents businesses that collectively generate $6 trillion in annual revenue, surveyed its members between October 31 and November 18.

(Reporting by Scott Malone in Boston, editing by Dave Zimmerman)