JPMorgan is preparing to bid for a portfolio being offered by UK Asset Resolution (UKAR) Ltd, a state-run "zombie bank" charged with winding down the assets of two failed British lenders, Bloomberg said, citing five people with knowledge of the matter.

JPMorgan will partner with CarVal Investors LLC to make the bid, Bloomberg added.

UKAR said in June that it had attracted several possible bidders for a $13 billion-pound mortgage book, named Granite, which comprises of loans from bailed-out Northern Rock and Bradford & Bingley.

Richard Banks, UKAR's chief executive, said at the time that a shortlist of potential buyers would be in place by the end of July, but warned that a deal was unlikely to be completed this year.

A group including investment bank Goldman Sachs Group Inc and U.S. buyout firm Blackstone Group LP had bid for Granite, sources told Reuters in June. Royal Bank of Scotland group Plc is also interested in the portfolio, the sources had said.

British finance minister George Osborne is keen to sell the government's banking assets to recoup taxpayers' money splashed out in a bailout of troubled lenders during the 2007-2009 financial crisis.

(Reporting by Richa Naidu in Bengaluru; Editing by Ted Kerr and Savio D'Souza)