* Talks aim to keep same ownership structure until March-sources
* Negotiations between Telefonica, Italy investors at advanced stage-source (Adds details, shares)
By Stefano Rebaudo
MILAN, Sept 20 (Reuters) - Spain's Telefonica is in talks with other core shareholders to keep Telecom Italia's ownership structure unchanged for six months, two sources with knowledge of the situation said on Friday.
That would give both the Spanish group and the Italian investors more time to study a reorganisation plan for the debt-laden telecoms group, possibly paving the way for its break-up.
Telefonica wants to avoid Telecom Italia falling into the hands of a competitor but is reluctant to increase its own stake.
"They are working on a solution that can allow Telefonica not to buy new shares in Telecom Italia and keep the status quo for a while," one of the sources said. "The idea is a postponement of six months, perhaps one year."
The source said the talks were at an advanced stage.
Telecom Italia's core shareholders, bound together in a holding company called Telco that owns 22.4 percent, have to say by Sept. 28 if they want to quit their pact early and ditch their stakes.
If the talks are successful, the investors would commit not to sell their stakes in the company until at least March 2014, even if they decide to quit the pact, according to the sources.
Telefonica is Telco's biggest shareholder. To varying degrees the other investors, Italian banks Mediobanca and Intesa Sanpaolo and insurer Generali, have signalled they are ready to sell their holdings.
Telefonica declined to comment, while the others did not immediately respond to requests for comment.
Telefonica has been studying various options to buy out the other Telco investors without adding to its own substantial debt burden, a source familiar with the situation said this week.
Another issue in the short-term is the Spanish group's desire to avoid anti-trust problems in Brazil, where it competes with the Italian company.
Telecom Italia shares extended losses after news of the talks to keep the status quo. At 1425 GMT the stock was down 2.8 percent at 0.574 euros.
The sources said that in future a merger between Telefonica and Telecom Italia was an option, but not the only one and it was possible the Spanish group could eventually sell its shares.
In hastily-convened talks on Thursday, Telecom Italia Chairman Franco Bernabe and core shareholders failed to bridge differences on how to relaunch the group ahead of a board meeting due on Oct. 3.
Telecom Italia, which risks having its credit rating being cut to junk in the coming weeks, has struggled to grow because of its 29 billion euro ($39 billion) debts and a deep economic downturn in its Italian home market. ($1 = 0.7384 euros) (Writing by Danilo Masoni; Editing by Silvia Aloisi and Anthony Barker)