* Stiefel family exercises option to sell stake
* Talks ongoing over terms
* Purchase price to be around 230 mln euros - source (Adds comment from Metro)
FRANKFURT, Jan 28 German retailer Metro will pay around 230 million euros ($310 million) to acquire a 2.97 percent stake in Europe's largest chain of electrical stores from one of its founders, a source close to Metro said on Monday.
The purchase from Leopold Stiefel will take Metro's stake in Media-Saturn to 78 percent, handing it a little more influence over the company.
Another of Media-Saturn's billionaire founders, Erich Kellerhals, owns a blocking minority of close to 22 percent and has regularly spoken out against Metro's management of the chain.
Wrangling over decisions meant Media-Saturn, which had 2012 sales of 21 billion euros, was late to set up websites to tap into growing demand across Europe for online sales of items from TVs to laptops.
Kellerhals pulled out of a Media-Saturn joint venture in China at the end of last year, saying Metro should have expanded there more quickly and aggressively.
Metro said earlier this month it would scrap the venture in China altogether given tough market competition.
Metro, which also runs cash-and-carry outlets, department stores and hypermarkets, said it had made provisions for the purchase of the stake in Media-Saturn and it would therefore have no effect on its results.
Stiefel, one of the founders of Media-Saturn, secured an option in 2002 to sell the stake to Metro. The family said talks were ongoing over the terms.
"I've devoted my life to Media-Saturn. And although I'm stepping down for reasons of age, it will remain close to my heart," Stiefel said, adding he will continue in an advisory role.
Metro's shares were down 0.55 percent at 22.79 euros at 0826 GMT, underperforming a 0.3 percent gain for the MDax index of medium-sized German companies. ($1 = 0.7421 euros) (Reporting by Matthias Inverardi and Victoria Bryan; Editing by Tom Pfeiffer)