The 19-country eurozone lost some economic momentum in August, largely because of a slowdown in Germany, a closely watched survey showed Monday, days ahead of another possible stimulus package from the European Central Bank.

Financial information company IHS Markit said its purchasing managers' index a broad gauge of economic activity for the eurozone fell to a 19-month low of 52.9 points in August from 53.2 the previous month. The fall was unexpected as the initial estimate for August was 53.3.

In spite of the fall, the eurozone is still growing, albeit sluggishly as anything above 50 indicates expansion. IHS Markit said the August reading is pointing to a quarterly economic growth rate of 0.3 percent.

The firm did not assign any fundamental reason to the slowdown, such as uncertainty related to Britain's decision in June to leave the European Union, but did note that Germany was "perhaps the biggest cause for concern" as output growth slowed to a 15-month low.

Italy and France also saw modest rates of growth while Spain remained the "standout performer" with another strong quarter of growth at around 0.7 percent.

The firm's chief economist, Chris Williamson, said the survey overall was "clearly disappointing" and suggested it may fuel expectations of a further stimulus package from the European Central Bank this week.

"The survey data will fuel expectations that the ECB would prefer not to wait before injecting more stimulus into the economy, adding pressure for policymakers to act later this week to help shore up confidence in both the outlook for the economy and the bank's commitment to its inflation target," he said.

The central bank has launched a series of stimulus measures to help the eurozone over the past couple of years, including cutting its key interest rate to zero. It is also pumping 80 billion euros ($90 billion) of new money into the economy every month by buying bonds from banks and companies in the hope of keeping a lid on borrowing rates in the real economy to encourage lending and promote business activity.

Williamson said the central bank may just extend the duration of its bond-buying program, which is currently set to end in March 2017, at its meeting on Thursday.