Santander UK has completed its near £3 billion takeover of smaller rival TSB in what it said marks the single biggest investment in Britain’s banking sector for more than 15 years.

Spanish-owned Santander said the deal went through on Thursday after recently securing the green light from regulators in the UK and Europe.

It will see the combined group become the UK’s third biggest bank for current accounts and fourth for mortgages, with nearly 28 million customers nationwide.

Santander, which is owned by Banco Santander, said there would be no immediate change for customers of Santander or TSB, who can continue using their accounts and cards in the same way.

Mahesh Aditya, Santander UK’s new chief executive, said: “This is excellent news for UK banking, with the acquisition representing the single largest investment in the sector for over 15 years.

“Bringing TSB into the Santander group strengthens competitiveness in the market and is an important step in creating the best bank for customers.”

Santander…