Germany's biggest technology company, Siemens, has announced some big managerial and structural changes.

Chief executive officer Heinrich von Pierer - viewed as one of the country's top managers - will resign at the end of January after 12 years at the helm and hand over to Klaus Kleinfeld, currently responsible for the group's telecommunications units.

Von Pierer, 63, is credited with streamlining the company, which manufacturers a wide variety of products including telephone switches, microwave ovens and train locomotives, and introducing US performance measures. One of his most recent coups was to force Germany's powerful IG Metall union into accepting a deal where some Siemens employees could keep their jobs if they agreed to work 40 hours a week instead of 35.As supervisory-board chairman, Von Pierer will however retain a powerful position in the company.

Kleinfeld, 46, made his mark turning around the group's troubled US business. He brings a US management style to the German company. A tough cost-cutter, Kleinfeld is expected to sort out a hodgepodge of unprofitable operations and focus on a smaller number of core areas with growth potential. Siemens currently has 13 operating divisions.

As a possible sign of changes to come, the group has already decided to merge its fixed and mobile network divisions effective the start of October this year.