U.S. consumer confidence unexpectedly weakened in August to its lowest in nine months as Americans turned more pessimistic about the short-term outlook, according to a private sector report released on Tuesday.

The Conference Board, an industry group, said its index of consumer attitudes fell to 60.6 from a downwardly revised 65.4 the month before. Economists had expected an increase to 66, according to a Reuters poll.

It was the lowest level since November. July was originally reported as 65.9.

"Consumers were more apprehensive about business and employment prospects, but more optimistic about their financial prospects despite rising inflation expectations," said Lynn Franco, director of The Conference Board Consumer Research Center, in a statement.

The expectations index tumbled to 70.5 from 78.4, while the present situation index edged down to 45.8 from 45.9.

Consumers' labor market assessment was mixed. The "jobs hard to get" index eased to 40.7 percent from 41 percent but the "jobs plentiful" index also declined to 7 percent from 7.8 percent.

Consumers were more concerned about price increases, with expectations for inflation in the coming 12 months climbing to 5.9 percent from 5.4 percent.