LONDON (Reuters) - The British arm of Spanish bank Santander (>> Banco Santander, S.A.) formally started the succession process on Tuesday for a new chief executive, with former Royal Bank of Scotland (>> Royal Bank of Scotland Group plc) executive Nathan Bostock considered the hot favourite for the job.

Santander UK CEO Ana Botin was last week appointed chairwoman of the Madrid-based Santander Group following the death of her father Emilio.

The British arm's board met on Tuesday and said in a statement that Bostock had assumed responsibility for operations and strategy, but it stopped short of naming him as the permanent replacement.

Bostock, 53, was appointed deputy chief executive last December with a view to eventually succeeding Botin as boss of the British business. He only joined Santander a month ago, after Royal Bank of Scotland (>> Royal Bank of Scotland Group plc) made him serve out notice.

(Reporting by Steve Slater; Editing by Crispian Balmer)

Stocks treated in this article : Banco Santander, S.A., Royal Bank of Scotland Group plc