(Rewrites throughout to add details and background)
WASHINGTON, April 22 (Reuters) - U.S. Supreme Court justices on Tuesday appeared skeptical over online TV startup Aereo Inc's position in a copyright fight with major media companies, but several raised concerns about how a ruling in favor of broadcasters could affect increasingly popular cloud computing services.
Aereo, backed by media mogul Barry Diller's IAC/InterActiveCorp, could be forced to shut down if the court rules for the companies challenging the startup. A win for Aereo could spur innovation in the television industry by paving the way to new, cheaper ways for consumers to watch shows. A decision is due by the end of June.
Aereo charges users a low monthly fee to watch live or recorded broadcast TV channels on computers or mobile devices. Aereo, which started in 2012, does not pay the broadcasters.
Aereo's fate was placed in the hands of the high court when Walt Disney Co's ABC network, CBS Broadcasting Inc, Comcast Corp's NBCUniversal and Twenty-First Century Fox Inc appealed a decision by the 2nd U.S. Circuit Court of Appeals in April 2013 that denied their request to shut Aereo down while litigation moved forward.
During a one-hour-long oral argument on Tuesday, several justices appeared troubled about a ruling that would deal a blow to increasingly popular cloud computing services in which personal files - including TV shows and music - are stored remotely on the Internet on servers from companies such as Google Inc, Microsoft Corp, DropBox Inc and Box Inc.
Justice Stephen Breyer told the networks' lawyer, Paul Clement, that his legal argument "makes me nervous about taking your preferred route."
Justices Anthony Kennedy and Samuel Alito were among others who raised similar concerns.
A number of justices also seemed skeptical about Aereo's business model. Chief Justice John Roberts questioned whether the technology used by the company had any purpose other than skirting copyright law.
"I'm just saying your technological model is based solely on circumventing legal prohibitions that you don't want to comply with," he told Aereo's lawyer, David Frederick.
Aereo subscribers can stream live broadcasts of TV channels on mobile devices using miniature antennas that the company hosts. The company says its service does nothing more than provide users what they could obtain with a personal TV antenna.
The broadcasters claim the service violates their copyrights on the television programs and represents a threat to their ability to control subscription fees and generate advertising.
Aereo, which is available in 11 U.S. cities, has never disclosed its user base. It is estimated to be miniscule compared to the 100 million U.S. customers who pay for television. But should Aereo prosper, it could threaten the $3 billion in so-called "retransmission fees" that research firm SNL Kagan estimates broadcasters get from cable and satellite systems.
The case is American Broadcasting Companies Inc, et al, v. Aereo Inc, U.S. Supreme Court, No. 13-461
(Editing by Will Dunham and Grant McCool)