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* Competition watchdog insists on "no single buyer" rule
* Rule set to spice up rights auction this summer
* Potential bidders await further details
By Alexander Hübner and Harro Ten Wolde
FRANKFURT, Feb 2 (Reuters) - Germany's top soccer league will not be allowed to sell exclusive rights for live television broadcasts after the country's competition watchdog insisted on a "no single buyer" rule for the imminent Bundesliga rights auction, three sources with knowledge of the matter told Reuters.
While German soccer fans may have to subscribe to more than one pay-TV service to watch all live broadcasts in future, the rule may yet drive up prices in an auction the Bundesliga' owner, the German Football League (DFL), hopes to conclude early this summer.
DFL voiced its opposition to the rule precluding any buyer from securing all the TV rights, one of the sources said, but the cartel office stood firm in an effort to foster competition.
Such a rule could undermine the strategy of Sky Deutschland, which holds all the Bundesliga live broadcast rights to the end of the 2016/17 season, having paid 2.5 billion euros ($2.73 billion) in 2012 to trump a bid by Deutsche Telekom.
Parent company Sky has encountered the same scenario in Britain, where it now shares English Premier League rights with telecoms group BT after one of the most high-profile broadcast auctions of recent times forced the rivals to shell out a combined 5.14 billion pounds ($7.4 billion), smashing analysts' expectations.
Coverage of leading clubs such as Bayern Munich, Borussia Dortmund and Schalke 04 has helped Sky Deutschland to record a 9 percent rise in subscriber numbers to 4.5 million.
Sky, which is 39 percent owned by Rupert Murdoch's 21st Century Fox, declined to comment on Tuesday, but it has previously said that it would like to continue to broadcast the Bundesliga..
NEW ENTRANTS?
The antitrust authority's involvement may not have the desired effect, however.
"Any new entrant would have to start from scratch. That will make it difficult to attack Sky's business model," one of the sources said.
However, there are number of potential buyers that could enter the fray.
Bertelsmann's RTL Group said it was interested in the Bundesliga rights in principle but declined to comment further.
RTL secured the live broadcast rights for the German national soccer team's qualifying matches for the 2016 European Championship and the 2018 World Cup.
Eurosport, owned by U.S. media company Discovery, has the rights for Bundesliga games in 23 European markets outside Germany. A spokeswoman said that the company looks at all rights case by case but declined to elaborate.
German sports marketing media group Constantin Medien is looking to participate in the auction, a source close to the company said, while ProSiebenSat.1 has said it would look at the available packages.
Deutsche Telekom will wait for more details on how the auction will be structured before deciding whether to join the contest, a person close the telecoms operator said. The company declined to comment.
Vodafone, which owns cable provider Kabel Deutschland, also declined to comment. ($1 = 0.9152 euros) ($1 = 0.6950 pounds)
(Additional reporting by Matthias Inverardi, Klaus Lauer, Joern Poltz and Peter Maushagen; Editing by David Goodman)
