The Eurozone private sector recovery strengthened further in September largely due to a strong upturn in services, preliminary data from Markit Economics showed Monday.

The flash composite output index rose more-than-expected to 52.1 in September, a 27-month high, from 51.5 in August. It was forecast to rise to 51.7.

The Purchasing Managers' Index for the service sector came in at 52.1, up from 50.7 in August. Services activity rose for the second month running, expanding at the fastest rate since June 2011.

Meanwhile, the manufacturing PMI fell to 51.1 in September from 51.4 in August. Nonetheless, manufacturing output rose for the third straight month.

"The overall rate of growth signaled by the Eurozone PMI remains modest, however, consistent with gross domestic product rising by a meager 0.2 percent in the third quarter," said Chris Williamson, chief economist at Markit.