Business sentiment in Germany remained unexpectedly robust in August, the Munich-based Ifo think tank said Tuesday.

The institute recorded an uptick of 0.3 points in its monthly gauge of the mood in German boardrooms, for which 7,000 executives are asked for their opinion of current economic conditions and a six-month outlook.

The better-than-expected results gave Germany's blue-chip DAX stock market a 3.2 percent boost in mid-morning trading. Analysts polled by news agencies had forecast a slight downturn in the index.

Confidence improved most of all in the construction, retail and services industries.

"The German economy continues to be a rock in turbulent waters," Ifo President Hans-Werner Sinn said.

The index, comprised of sub-indexes, rose from 108 to 108.3 points overall. One sub-index measuring current business rose to 114.8 points, its highest level since April 2014, while another measuring outlook for the future slipped to 102.2 points.

cjc/uhe (AP, AFP, dpa, Reuters)