Fisher will join next year as a member of the group executive committee (GEC) of the newly named Lloyds Banking Group to head the integration of high street rival Hbos.

An RBS executive director, Fisher is currently seconded to ABN Amro as chief executive, overseeing the integration of the Dutch bank's business following its acquisition last year.

He has been a director of RBS since March 2006 and chief executive of the manufacturing division - which employs 25,000 people supporting IT, property, purchasing and back-office services functions - since 2000.

Fisher joined RBS in 2000 after the bank acquired NatWest, where he was chief operating officer. He then led the integration of NatWest, spanning 400 work streams, 22 billion records and 18 million customer accounts, including £158 billion in deposits.

Eric Daniels, group chief executive, Lloyds TSB, says: "I am delighted Mark is joining us; he has a deep expertise in banking and his proven track record in dealing with highly complex integration activity will be a great asset to the new Lloyds Banking Group."

Fisher will be charged with making significant savings for the new group, which yesterday said it expects to reap £1.5 billion annually from consolidation of technology, branch closures and job cuts.

In retail banking, Lloyds TSB expects to realise £790 million in savings over the next three years as it moves to close branches and call centres and consolidate processing and technology platforms.

Similar exercises across the insurance and investments arms, within wholesale and international banking and through the integration of central and support group functions will lead to a further £710 million in cost synergies.

The plans have raised fears that up to 30,000 jobs could be shed as a result of the merger, although Lloyds TSB has refused to provide any details.