Cash-rich German carmaker Volkswagen AG and its ailing majority owner Porsche SE must decide soon whether to integrate or not, VW's home state of Lower Saxony said on Monday. We need to clarify now whether each will go his own way or whether there is a common solution, conservative state premier Christian Wulff said at an event sponsored by the Christian Democrats in Berlin, adding the state and VW both saw the advantages of a deal. Wulff said he felt a certain irritation after Porsche accused Volkswagen and Lower Saxony, the carmaker's second-largest shareholder, of issuing an ultimatum for Porsche to agree to a deal by the end of Monday. Apparently not all facts are known to everyone, he explained. Both Volkswagen and Lower Saxony deny making an ultimatum that Porsche Chairman Wolfgang Porsche and his deputy Uwe Hueck in a joint statement on Saturday denounced as detrimental to the entire cause, pledging not to give in to this blackmail. Wulff called on both sides to concern themselves with their core business and not become entangled in power struggles. (Reporting by Andreas Moeser; Writing by Christiaan Hetzner)