EMILIO Botin, one of Spain's most powerful men, who transformed Santander from a small domestic lender into the eurozone's biggest bank, has died of a heart attack aged 79.

His eldest daughter Ana Botin, currently head of Santander's British business, was approved as the bank's new chairman at a board meeting yesterday.

The move could spark controversy, with banking dynasties coming under ­criticism after a scandal at Portugal's Banco Espirito Santo, where the founding family's holdings are being investigated over financial irregularities.

But other experts said Ms Botin, who has spent most of the last 25 years at Santander, could provide welcome continuity.

Mr Botin, known as El Presidente to colleagues and the third generation of Botins to run Santander, was at the forefront of a drive to create global banks, offering a one-stop shop to multinational companies and a range of services to consumers.

He used a keen eye for deals to spread Santander's red-liveried brand with its stylised "S" logo around the world, amassing more than £1 trillion of funds and nearly 200,000 employees.

Spanish Prime Minister Mariano Rajoy said: "He was a man who has been able to make Banco Santander the most important bank of our country. I had a meeting with him last week and he was well and in good form. [His death] has been a surprise and a blow."

Mr Botin's aggressive expansion of Santander saw him join forces with disgraced RBS boss Fred Goodwin when the banks teamed up for what turned out to be a disastrous take­over of Dutch bank ABN Amro.

In 2004, Mr Botin had also snapped up Britain's Abbey National for more than £9 billion and while partners RBS and Fortis were driven to seek state bailouts after a carve up of ABN Amro on the eve of the financial crisis, Santander emerged comparatively unscathed with the Dutch group's healthier Brazilian arm.