Confidence among German investors plunged in August, a monthly survey showed Tuesday, as fears for growth prospects in Europe's largest economy made themselves felt.

The ZEW institute's closely-watched barometer fell to 10.0 points in August from 17.5 in July, well short of the 15.0 points predicted by analysts surveyed by data company Factset.

"The very significant fall in business expectations reflects nervousness about the future path of growth in Germany," ZEW chief Achim Wambach said in a statement.

"Above all, weaker-than-expected growth in exports and the growing scandal in the car industry contributed," he added.

German exports booked an unexpected fall in June, figures released earlier in August showed.

Meanwhile, widening suspicion over diesel emissions cheating has prompted politicians to moot draconian measures to reduce air pollution, casting a pall over the country's vital auto sector.

Looking to other elements of the survey, financial players remained happy with Germany's present economic situation, with that index almost flat at 86.7 points.

In the same measure for the eurozone, confidence grew sharply, adding 9.7 points to reach 38.4.

But confidence in the outlook in the coming months for the 19-nation single currency area shed 6.3 points to reach 29.3.

"August's fall in investor sentiment probably reflects the euro's continued rise and recent falls in equity prices" rather than underlying economic weakness, Capital Economics analyst Stephen Brown commented.

Direct surveys of businesspeople rather than the financial sector point to continued growth ahead, he noted.

ZEW questioned 213 analysts and institutional investors between August 7 and 21 to compile its index.