By Christoph Steitz

FRANKFURT (Reuters) -Volkswagen on Thursday said that a major IT outage, which had caused most of its German plants to halt production, was resolved overnight and its global production network was up and running again.

The incident, which VW said began at 1030 GMT on Wednesday and was disclosed late that evening, impacted the entire Volkswagen group, which includes the Porsche AG brand and Audi, highlighting the vulnerability of network infrastructure at Europe's largest carmaker.

"The IT infrastructure problems in the Volkswagen network were resolved during the course of the night and the network is stable again," Volkswagen said, without providing details on the impact or cause of the incident.

The company said it was unlikely that an external attack was the cause of the incident.

"The affected applications are currently being restarted. The global production network is up and running, and production is expected to proceed as planned," it said, adding individual systems may still be affected during a transitional phase.

The incident comes a month after a production system malfunction brought domestic output at Toyota, the world's biggest-selling automaker, to a halt.

The outage affected Volkswagen's German sites in Wolfsburg, Emden, Osnabrueck, Hanover, Dresden and Zwickau, as well as component factories in Braunschweig, Kassel, Chemnitz and Salzgitter.

"There are still no indications that the disruption was caused by external influences," Volkswagen said.

The event puts a spotlight on the safety of infrastructure at Germany's top corporations and drew comments from Transport Minister Volker Wissing, who called for better protection.

"We need safety systems here that work," Wissing told broadcaster RTL/n-tv. "It must be clear to everyone that digital infrastructure is critical infrastructure."

(Reporting by Christoph Steitz, Writing by Miranda Murray; Editing by Kim Coghill, Elaine Hardcastle)