The deal was expected to be concluded by the end of 2011 but in a statement VW said that continued legal hurdles have left it unable to properly assess the value of Porsche.

These legal issues relate to Porsche’s attempt to acquire VW in 2008, which failed and have left it subject to ongoing proceedings and actions in Germany and the US for alleged market manipulation.

VW added that it is looking at other measures ‘for achieving the goal of creating an integrated automotive group with Porsche in addition to the put/call options laid down in the Comprehensive Agreement’ and will present any results to the supervisory board before the end of the year.