Eurozone private sector business activity slowed sharply in January against a backdrop of volatile financial markets and uncertainty about the global outlook, a key survey showed Friday.

Data monitoring company Markit said its closely watched Composite Purchasing Managers Index (PMI) fell to 53.5 points in January from 54.3 in December, hitting an 11-month low.

The reading was still well above the 50-point boom-or-bust line, showing the 19-nation eurozone economy continued to expand.