Industrial production in the eurozone was weaker than expected in January when output stalled compared to December and grew 2.5 percent over 12 months, the EU's Eurostat data agency said Friday.

The figures, which were adjusted for seasonal variations, fell short of private economists' forecasts for an increase of 0.5 percent over one month and 2.8 percent over one year.

They also marked a slight slowdown from December when industrial production grew 0.2 percent over one month and 2.8 percent over 12 months.

Eurostat revised its December figures from an original estimate of a 0.1 percent increase over one month and a 2.5 percent rise over one year.

In the 25 nation European Union, industrial output was also stable in December over one month and 2.4 percent over one year.

Economists blamed the weaker-than-expected January performance of the eurozone's factories on the drop in energy production.

"The stagnation in eurozone industrial production in January was both disappointing and unexpected, even allowing for the fact that the overall performance was dragged down by a sharp drop in energy output," said economist Howard Archer with consultancy Global Insight.

A breakdown of eurozone January data by sector showed that energy output by eurozone plants slumped 3.0 percent over one month while production of non-durable consumer goods, such as food and clothing, eased 0.6 percent.

Output of capital goods used to make other products rose 1.1 percent, while both intermediate goods, or semi-finished goods, and durable consumer goods such as appliances or furniture increased 0.4 percent.

Despite the weaker-than-expected overall performance, Lehman Brothers economist Sandra Petcov was confident that the underlying conditions were in place for firm growth.

"Altogether, with favourable base effects in place, euro-area industrial production still looks on track for a healthy quarterly gain in Q1, supporting a rebound in GDP growth," she said.