Lloyds TSB suffered a major blow today when it emerged one of its star executives is moving back to America.

Terri Dial, highly rated head of the bank's retail arm, has been poached by Citigroup to lead a turnaround of the stumbling Wall Street giant.

Dubbed the human cyclone because of her feisty style, the 58-year-old Californian is credited with salvaging Lloyds. Her departure leaves a hole at executive level and removes a potential successor to chief executive Eric Daniels.

Lloyds said Dial will stay at the bank for an unspecified period "to ensure an orderly transition". It said it had begun a search for a replacement.

Dial's salary was £570,000, but bonuses and other payments took the total closer to £2 million.

She joins Citigroup at the rockiest period in its history. The bank has written off billions of dollars because of the subprime mortgage fiasco, and analysts expect worse to come.

Chief executive Vikram Pandit wants Dial to stem losses at the consumer arm, which is suffering as recession bites in the US. She can be expected to take a no-nonsense approach, given the ruthlessness with which she shut Lloyds branches in the face of protests.

The move may increase the perception that New York is again becoming the most powerful financial centre in the world, replacing London.

Bob Diamond, the American who heads Barclays Capital, is to split his time between Wall Street and the City as the bank looks to build its US investment banking presence.

Dial made her name at Wells Fargo, starting as a cashier and rising to chief executive. She turned the bank from a sleepy regional player into one of the most successful banks in America.

Lloyds shares today fell 4½p to 455p.