UPDATE 1-Porsche owner families back Qatar deal, paper

(Adds German weekly report on impending Qatar deal)

FRANKFURT, June 13 (Reuters) - A majority of members in two families controlling Porsche (PSHG_p.DE: Quote, Profile, Research) back a deal for the Gulf state of Qatar to acquire a 25 percent stake in the German luxury carmaker, Der Spiegel magazine said.

It said Qatar and adviser Credit Suisse have already completed their due diligence on June 8.

The Porsche and Piech families own the common shares in the company and have so far never allowed outsiders to acquire any of it.

Frankfurter Allgemeine Sonntagszeitung weekly, citing banking sources, reported the deal with Qatar is now on the brink of being approved and that this weekend, the modalities for Qatar's entry as a shareholder are being negotiated.

A Porsche spokesman told Reuters: "When talks are going on, we will not give you any updates."

Sources said a decision is "very well possible" in June.

Der Spiegel said Porsche chief executive Wendelin Wiedeking's timetable would be for the Porsche supervisory board to hold a special meeting in early July to approve a capital increase.

Porsche shareholders would then approve the capital hike in a general shareholders meeting in early September so that 4-5 billion euros ($5.63 billion) in new money could be raised by November at the latest.

The new capital could help lift Porsche SE's balance sheet, which is saddled with nine billion euros of net debt it had incurred to pave the way for the now aborted plan to take over Volkswagen (VOWG.DE: Quote, Profile, Research).