UPDATE 1-Porsche to debate 5 bln eur Qatar stake buy -source

* Carmaker calls special board meeting on July 23

* Porsche management concludes talks with Qatar - source

* To discuss possible sale of Porsche AG stake in VW

* Porsche shares up 1 pct

(Adds background, analyst comment, share price)

STUTTGART, Germany, July 10 (Reuters) - Indebted automotive holding group Porsche SE (PSHG_p.DE) has called a special board meeting to discuss Qatar's possible investment worth around 5 billion euros ($6.97 billion), a source said on Friday.

The source said the extraordinary supervisory board meeting was scheduled for July 23.

The Stuttgart-based group's board will also debate on that day a possible sale of a 49 percent stake in its wholly owned sports car unit, Porsche AG, to Volkswagen (VOWG.DE), the person added. Porsche SE, which controls 51 percent of VW's voting stock, confirmed that Chairman Wolfgang Porsche has called an extraordinary supervisory board meeting for July 23.

The source said Porsche management has already concluded its negotiations with Qatar and was ready to present its concept to the supervisory board.

The value of Qatar's possible investment was estimated at more than 5 billion euros, the source said. The market had speculated the investment would be worth around 2-3 billion euros.

The source said the concept included the acquisition by Qatar of a stake in Porsche SE as well as purchasing options on VW stock which are still held by Porsche.

It is possible that Qatar would acquire both voting and preferred shares in Porsche SE, which now has a market capitalisation of nearly 7.4 billion euros, the source added.

DZ Bank analyst Michael Punzet said it was still unclear whether Qatar would invest directly in Porsche or invest in Porsche's options in VW or both.

"The mentioned amount would fit to the exercise of these options, assuming a strike (price) of around 80-90 euros for options on 58.8 million VW ordinaries," Punzet said.

Punzet reiterated his "sell" stance on Porsche shares, citing the high degree of uncertainty and the possibility that Porsche's board would not make a final decision on July 23.

Porsche shares gained 1 percent by 1434 GMT in a lower German market. Volkswagen shares eased 0.1 percent.

(Reporting by Hendrik Sackmann, writing by Marilyn Gerlach; Reuters Messaging: marilyn.gerlach.reuters.com@reuters.net; +49 69 7565 1279)) ($1=.7173 Euro)