Factory activity in the U.S. mid-Atlantic region unexpectedly contracted in February as new orders plunged, a survey showed on Thursday.

The Philadelphia Federal Reserve Bank said its business activity index tumbled to -6.3, from 9.4 in January. That was far below economists' expectations for 8.0, according to a Reuters poll.

A reading above zero indicates expansion in the region's manufacturing. The survey covers factories in eastern Pennsylvania, southern New Jersey and Delaware.

New orders fell to minus-5.2 from 5.1. Growth in the employment component decelerated, with the index down to 4.8 from 10.0.

But survey respondents' view on the coming months improved, with the gauge of business conditions for the next six months rising to 40.2 from 34.4.

The survey is seen as one of the first monthly indicators of the health of U.S. manufacturing leading up to the national report by the Institute for Supply Management.