Factory activity in the U.S. mid-Atlantic region contracted in May as new orders fell to their lowest level in almost a year, a survey showed on Thursday.

The Philadelphia Federal Reserve Bank said its business activity index dropped to minus 5.2 from 1.3 in April, worse than economists' expectations for a slight gain to 2.4.

Any reading below zero indicates contraction in the region's manufacturing. The survey covers factories in eastern Pennsylvania, southern New Jersey and Delaware. 

New orders fell to minus 7.9 from minus 1, the lowest level since June of last year. The gauge of the number of employees declined to minus 8.7 from minus 6.8.