(Reuters) - Spanish banking giant Banco Santander is pushing to expand its U.S. operations through a partnership with Verizon by tapping into the telecom major's vast customer base, a source familiar with the matter said on Tuesday.

The partnership will let Verizon customers to earn bill credits by opening high-yield savings accounts with Santander's new digital bank platform, the source said.

Verizon did not immediately respond to a Reuters request for a comment.

Santander has one of the biggest auto-lending businesses in the United States. It wants to use the U.S. to build its own technology platform for consumer banking, including digital-only banking and consumer finance.

The bank formally launched its U.S. digital bank in October, offering high-yield savings accounts, which could help fund up to $30 billion in loans for vehicle purchases and broaden its retail business in the U.S.

Santander is one of the few European banks with a retail presence in the U.S. market following the exit of rivals BBVA and BNP Paribas. It has 409 branches mainly in nine states in the Northeast.

The lender will also consider other partnerships as it aims to become a full-service digital bank in the U.S., Ana Botin, Santander's executive chair, told Wall Street Journal in an interview, which had first reported the news.

In October last year, Botin said she expected the bank to have a full-service digital bank in the U.S. by the end of 2025 - a crucial step, as Santander's U.S. business has been generating subpar returns.

Last month, the Spanish bank announced various investments amounting to over $2 billion in Mexico over the next three years.

(Reporting by Rajveer Singh Pardesi, Kritika Singh and Rishabh Jaiswal in Bengaluru; Editing by Alan Barona and Mrigank Dhaniwala)