Investments surged by 13.4% from 7.2% in the previous quarter, offsetting a pronounced slowing of export growth, which was at 5.7% compared to 9.1% in April-June. The growth of domestic consumption held steady at 3.5%.

The high investment growth was the result of brisk growth of gross fixed capital formation as well as changes in stocks. It contributed 0.5 of a percentage point to GDP growth, mostly as a result of an almost 20% spike in construction investments.

Household final consumption expenditure remained at the same level as in the third quarter of 2017.

Despite the slowdown in exports, however, external trade had a positive impact on economic growth since imports declined in at an even faster pace than exports. The external trade surplus contributed 1.7 percentage points to the economic growth.

"The differing dynamics and scope of exports and imports led to a record external trade surplus, hence the high contribution to GDP growth," statistician Romana Korenič said.

"External demand is clearly slowing down... On the other hand we have a surge in investment and construction, which is definitely a consequence of pre-election stories," the Statistics Office's deputy director Karmen Hren said.

She added that it was unclear whether construction investments will continue. "This is why the signals indicating which way [the economy] will turn are not perfectly clear," she said.

A recent analysis by the Chamber of Commerce and Industry (GZS) concluded that local elections boost GDP by half a percentage point because of high investment expenditure.

Total employment was at 1,022,053 persons and increased by 2.8% year-on-year, the data show.

The high rate of growth in the third quarter was expected given the current position in the economic cycle, but a slowdown is projected in the final quarter and in 2019 as the impact of a contraction in global trade, already evident in export figures, becomes more pronounced.

Several forecasters have also warned that the Slovenian economy is close to capacity, with nearly full employment gradually exerting a drag on growth.

IMAD, the government's macroeconomic forecaster, said today that growth remained broad-based, while companies are in good shape financially and financing terms remain favourable.

But it said it was "somewhat surprising" that the growth of household spending remained at the same level considering that wages have been rising and the labour market situation has been improving.