Warren Buffett's Berkshire Hathaway Inc (BRKa.N) will walk away from its US$9 billion acquisition of Oncor Electric Delivery Co if the deal is delayed, an attorney for the parent company of Texas' largest utility told a bankruptcy judge on Wednesday.

Energy Future Holdings Corp, the bankrupt owner of Oncor, disclosed Berkshire Hathaway's warning as the judge considers a request by the utility's biggest creditor, hedge fund Elliott Management Corp, to hold up the deal with Buffett so it can put together its own US$9.3 billion bid for Oncor.

"(Berkshire Hathaway) may not go away forever, but they have told us and we have no reason to doubt them, that they will go away," Energy Future's lawyer Chad Husnick told U.S. bankruptcy court Judge Christopher Sontchi at a hearing in Wilmington, Delaware.

"They may come back but it's ... going to be for a lower price," Husnick added.

Berkshire Hathaway's deal for Oncor is due to be approved by a bankruptcy court on Aug. 10, but Elliott is asking for a delay of 35 to 40 days so it can put together financing for its own bid for the utility.

If Elliott's request for a delay is granted, Berkshire has the right to end its deal, according to court papers.

Energy Future filed bankruptcy three years ago, and two earlier deals for Oncor fell apart after facing regulatory hurdles.