* State premier "irritated" by Porsche accusation
* Says Porsche does not have all the facts
* Remains in favour of deal between the two carmakers
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FRANKFURT, June 29 (Reuters) - Lower Saxony, Volkswagen's second-largest shareholder, again pushed VW and Porsche to break a deadlock in merger talks on Monday as the two German carmakers squabbled over a deal.
Disagreements among Porsche's owning families and questions about preconditions for an investment by Qatar have held up progress toward creating a combined company, people close to the negotiations said.
"We need to clarify now whether each will go his own way or whether there is a common solution," Christian Wulff, premier of the German state of Lower Saxony, said at 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, which owns a blocking minority in Europe's biggest carmaker, of holding a gun to its head to agree a deal quickly.
"Apparently not all facts are known to everyone," he said.
Volkswagen and Lower Saxony deny making any ultimatum which Porsche chairman Wolfgang Porsche and his deputy Uwe Hueck said in a joint statement on Saturday was "detrimental to the entire cause".
Porsche said a document containing "deadlines" was sent to Wolfgang Porsche last week.
Porsche dismissed as unworkable any deal which involved a partial sale of its sports car business to VW, noting this would let banks call immediately a 10.75 billion euro ($15.0 billion) syndicated loan they awarded Porsche in March.
Porsche and Volkswagen have been in talks to create an "intergrated" automotive group after Porsche's 9 billion euro debt burden forced it to drop plans for a full takeover of VW. Porsche owns a 51 percent stake of VW voting shares.
But progress toward creating a combined company stalled after Porsche chief executive Wendelin Wiedeking sought investment from sovereign wealth fund Qatar Investment Authority (QIA).
Porsche said last week talks with Qatar had "entered the final stretch" but it has so far failed to secure an agreement. QIA chief executive Hussein al Abdullah would not comment.
Qatar wants to learn more detail about combining VW and Porsche before committing to an investment in Porsche Automobil Holding SE, a person familiar with the talks said.
Key to any progress is the resolution of a dispute between the Porsche and Piech clans who own Porsche. Wolfgang Porsche opposes a sale of the Porsche AG sports car business to VW.
His cousin Ferdinand Piech, the chairman of Volkswagen, has in contrast been pushing for months for a sale of Porsche AG that would give the VW group its 10th brand.
VW is reluctant to continue talks with Porsche until the question of Porsche's Qatar investment is resolved, a person close to VW said.
VW finance director Hans Dieter Poetsch said this month that creating a combined VW-Porsche was "a demanding task. Important questions need to be resolved beforehand. We're seeking ways, if there are any, to build an integrated firm." (Reporting by Andreas Moeser, Hendrik Sackmann, Jan Schwartz and Edward Taylor; Editing by Dan Lalor)) ($1 = 0.7143 euro)