Sony Corporation has admitted its $5bn (£2.7bn) bid for MGM, the film studio behind Ben-Hur and the Wizard of Oz, has run into "complications".

The public admission confirms speculation that Sony is losing ground to companies such as US media conglomerate Time Warner which are also interested in buying the movie studio.

When asked how the talks were progressing, Sony chairman and chief executive Nobuyuki Idei told Reuters: "There are some complications ... It's up to the MGM management now."

It is understood Sony has hit roadblocks with its private equity partners in the deal, Texas Pacific, Providence Equity Partners and Credit Suisse First Boston, although it has not stopped talking to MGM.

The structure of the deal is understood to be complicated. Sony would get a minority stake and the "splitting of the winnings" is causing tension, according to a source close to the negotiations.

Sony and its fellow investors are planning an all-cash bid in which MGM would remain separate from Sony Pictures.

Sony has been in talks with MGM for months. An agree ment to talk exclusively to Sony ran out at the end of May, prompting interest from other parties.

Sony wants to buy MGM as part of a strategy to boost the content it produces to complement its electronics division. It owns Columbia Pictures, which it bought more than 10 years ago. It is understood to have already completed due diligence on MGM.

Time Warner is believed to be making progress in its examination of the MGM accounts in preparation for a cash and shares bid that would value MGM at about $5bn.

Any sale of MGM would give 87-year-old billionaire Kirk Kerkorian, who owns a 74% controlling stake, a large windfall. Time Warner's bid, which would give Mr Kerkorian a large chunk of the conglomerate's shares rather than cash, is understood to be more tax advantageous, which could give it an edge.

One source close to the negotiations said Mr Idei's comments were just "spin".

"It's their spin because they are feeling the heat from Time Warner," said the source. "They are having trouble with their equity partners and the agreement on financing. It is not the price that is the issue, that was set from day one."