U.S. manufacturing activity contracted for a 14th straight month in September, according to a closely-watched survey that may not fully reflect the economic fallout of the Sept. 11 attacks on U.S. cities.

The National Association of Purchasing Management reported on Monday its monthly index slipped to 47.0 in September after a jump to a nine-month peak of 47.9 in August raised hopes that the sector, locked in its worst slump since the 1990-1991 recession, was recovering.

A reading under 50 indicates that manufacturing activity -- nearly one-sixth of the overall economy -- is contracting. The NAPM index has now held below that level since August 2000.

But the index is still solidly above a decade low of 41.2 in January, and the September report showed new orders and factory production both grew for a second straight month, although at a slower pace than in August.

NAPM said some survey respondents indicated that it was too early to fully determine the effects of the Sept. 11 attacks.