* Volkswagen executive committee says EGM to be pushed back
* Poetsch to be named to supervisory board by court
* Law firm Jones Day leads investigation
* Management to update public next week (Adds executive committee comment, details on Poetsch appointment)
FRANKFURT, Oct 1 (Reuters) - Volkswagen expects it will need at least several months to get to the bottom of the rigging of emissions tests on its diesel vehicles, which has turned into the biggest business crisis in its 78-year history.
The executive committee of VW's supervisory board said it came to that conclusion after U.S. law firm Jones Day, hired to lead an independent investigation, updated it on its battle plan on Wednesday.
This means that Volkswagen should push back an extraordinary general meeting planned for Nov. 9 - at which finance chief Hans Dieter Poetsch was due to be named to the supervisory board - the committee said in a statement on Thursday.
"In view of the time available and the matters to be considered, it would not be realistic to provide well-founded answers which would fulfil the shareholder's justified expectations," it said, adding a court would appoint Poetsch to the board, after which he would be elected chairman.
Regardless, management will inform the public next week of any solutions it has found, it said, without being more specific.
Europe's biggest carmaker has admitted cheating in diesel emissions tests on around 11 million diesel vehicles. The scandal sent the Wolfsburg-based company's stock sharply lower and forced out long-time CEO Martin Winterkorn, who has been replaced by Porsche boss Matthias Mueller.
The company also named Frank Witter, the head of VW's financing arm, as the new CFO to replace Poetsch, confirming an earlier Reuters report. (Reporting by Maria Sheahan; Editing by Harro ten Wolde and Susan Thomas)