Private-sector output in the euro zone failed to live up to expectations for November, fueling concerns that the region's economic recovery is faltering.
Euro zone November flash composite purchasing manager's index (PMI) data from Markit came in at 51.4, below forecasts by analysts polled by Reuters of 52.3, and below October's final reading of 52.1.
Carsten Brzeski, chief economist at ING, said Thursday's figures "cannot simply be ignored."
"They fit into the picture of an economy which is struggling to gain momentum and leave stagnation behind," he said.
Activity in the region's manufacturing sector fell to 50.4, down from 50.6 in October while in the services sector there was a drop to 51.3, down from 52.3 in October.
The figures could put more pressure on the European Central Bank to increase stimulus measures, such as buying government bonds, a move that Germany has so far opposed.
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Nicholas Spiro, head of Spiro Sovereign Strategy, said the data spoke volumes about the breadth and depth of the economic downturn in the euro zone "which has spread deep into the core of the bloc."
"The euro zone economy is now in significantly worse shape than at the time of the severe escalation of the financial crisis in 2011," he said.
Following the data, the euro fell 0.3 percent to 1.2511 against the dollar and was down 0.2 percent against sterling, at 1.5644. The Euro Stoxx 600 Index also fell and was trading down 0.4 percent after the data was released.
The euro zone data was preceded by disappointing figures for Germany and France, the euro zone's largest and second-largest economies respectively.
Business output fell markedly in Germany in November, according to Markit, adding to concerns over the health of the euro zone's largest economy.
Markit's flash composite PMI fell to 52.1 in November -- a 16-month low -- and down from October's final reading of 53.9.
Activity in the manufacturing sector fell to 50.0, down from 51.4 in October and below forecasts. In the services sector meanwhile, flash data showed a drop to 52.1, down from 54.4 in October.
Meanwhile in France, data released earlier on Thursday showed the country's private sector economy continued to contract in November.
Markit's flash composite PMI for the euro zone's second largest economy edged up to 48.4 in November, from the final figure of 48.2 in October. The 50-point mark separates contraction from expansion.
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While service providers reported the slowest fall in activity of the current three-month period of decline, manufacturers indicated the sharpest reduction in output since August, Markit said.
The manufacturing PMI fell to a three-month low of 47.6 below October's final reading of 48.5 and below a forecast of 48.8 by analysts polled by Reuters. The services PMI hit a three-month high of 48.8, up from October's final reading of 48.3. Analysts had forecast a lower reading of 48.5.
- By CNBC's Holly Ellyatt, follow her on Twitter @HollyEllyatt. Follow us on Twitter: @CNBCWorld.