The Reuters euro zone Purchasing Managers' Index hit the lowest level in its four-year history in September, underlining the weakness of the region's economy even before the attacks on the US.
The survey said manufacturing in the 12-nation euro zone contracted in September at the sharpest pace since the series began in June 1997 as companies shed jobs, cut production and attracted less new business.
The headline index fell to 45.9 from 47.5 in August. It has been below the 50 line that divides growth from contraction for six straight months, signalling that the region's manufacturing sector has entered recession.
All the companies were surveyed after the September 11th attacks.
However, NTC Research, which conducts the poll, said it "found no evidence . . . that the terrorist attacks on the US had any impact on this month's data."
It said any impact from the attacks was more likely to show up in future months' surveys of the manufacturing sector "due simply to the nature of their activities and the proximity of the data-collection period to the terrorist attacks".
NTC said: "It remains far to early to speculate as to whether the manufacturing downturn is bottoming out".
The PMI manufacturing survey asks managers at 2,500 manufacturing firms to rate activity measures such as output, new orders and employment as better, worse or the same compared with the previous month.
All three measures fell sharply in September. Output at 46.6 and new orders at 44.3 both set new lows for the series, and the employment index at 47.9 showed the sharpest rate of contraction since January 1999.