Lloyds Banking Group's Chairman and Chief Executive Officer have been summoned to provide evidence on its failed deal to sell more than 630 branches to The Co-operative Group, according to Sky News on Tuesday.The Treasury Select Committee has invited Sir Win Bischoff and Antonio Horta-Osorio to share their perspective on the now-defunct transaction with the struggling UK retail business which includes The Co-operative Banking Group division.They are expected to appear before the committee later this month and to face tough questioning over why they allowed the deal to progress so far despite public concerns about the group's capital reserves. Their appearance will come days after the publication of a report that will make proposals for spurring competition in retail and business banking.It is understood Sir Bischoff and Horta-Osorio will also be asked whether Lloyds was put under political pressure to select Co-op as the preferred bidder over investment vehicle NBNK.The 41%-taxpayer owned lender's agreement to sell the branches to the Co-op was applauded by Chancellor George Osborne and Business Secretary, Vince Cable as a milestone move in reforming British banking.The deal fell through after it emerged that Co-op's existing business was significantly under-capitalised. Co-op's credit rating has been downgraded several times and it has seen the departure of number of top executives. Shares in Lloyds rose 1.28% to 62.41p at 14:41.RD