Royal Bank of Scotland said its finance director, Nathan Bostock, had resigned to join Spanish bank Santander after just 10 weeks in the job, dealing a major blow to the state-backed lender's turnaround efforts.
RBS said in a brief statement Bostock had on Tuesday evening told the board his intention to resign and would formally resign soon.
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The statement was rushed out after Sky News reported Bostock had quit to return to Santander UK, where he had previously held several positions, including chief financial officer.
Santander confirmed late on Wednesday that Bostock would be named chief risk officer and deputy CEO of its UK arm, which is due to be spun off and separately listed.
Given Ross McEwan's recent appointment as RBS chief executive officer, Bostock may have opted to join Santander UK as the CEO role there could become available before the top job at RBS. Santander UK Chief Executive Ana Botin has been tipped as a possible successor to her father Emilio Botin as chairman of the Madrid-based group, maybe once the UK arm is floated.
Bostock was appointed as RBS finance director on Oct. 1.
The news is a major blow to McEwan, who is conducting a review of the bank's strategy and operations, to be released in February.
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McEwan has been hit by IT problems, which last month caused more than 1 million RBS customers to be left stranded after a computer systems failure.
Bostock was previously head of RBS's restructuring and was expected to play a key role alongside McEwan to create a 38 billion pound ($62.42 billion) internal 'bad bank' announced last month.
Bostock had previously said he planned to leave RBS to join Lloyds Banking Group in 2011, but changed his mind after Antonio Horta-Osorio, the Lloyds chief executive, took a period of sick leave.