The eurozone economy has this month suffered its biggest jolt since the aftermath of the September 2001 terrorist attacks, with global financial turmoil hitting the services sector particularly hard, according to a closely watched survey.

The unexpectedly steep fall on Friday in the eurozone purchasing managers’ index – the third consecutive monthly drop – could knock policymakers’ previous confidence that the 13-country eurozone economy would escape largely unscathed from the US subprime mortgage crisis.