BRUSSELS: Eurozone economic activity slowed more than first thought in September, a key business survey showed on Monday, adding to concerns over the outlook.

Data monitoring company Markit said its revised September Purchasing Managers Index (PMI) fell to 53.6 points, compared with a first reading of 53.9 points.

The PMI, a closely watched indicator, stood at 54.3 points in August, well above 50-point boom-or-bust line as holding near the best performance in four years.