Banco Banorte, which is owned by the company, already has 12 million clients, making it the second largest in the country when measured by credit portfolio.

"There's a segment of our clients that today demands a 100% digital service," the group's president, Carlos Hank, said in an interview with Reuters.

Hank said Banco Banorte would continue to operate through its network of branches and its own mobile application, adding that bineo would not take clients away from the established bank. The launch pits bineo against smaller, all-online banks such as Brazil's Nubank and Argentina's Uala.

"We want to be a bank that will be able to offer its clients a mortgage, a credit card, a car loan," Hank said.

In Mexico, the financial sector is dominated by the local units of Spain's BBVA and Santander, as well as Citigroup. Banco Banorte is the largest local bank.

However, official data shows that a third of adults in Mexico do not have any type of formal financial product. More than a fifth of its 126 million people also do not have access to the internet.

"There's still a lot to do," Hank said, adding that bineo has a competitive advantage: the backing of Grupo Financiero Banorte.

Last week, Santander Mexico announced plans to launch its Openbank digital banking service in the coming months. In July, Hey Banco, backed by Banregio Grupo Financiero, received authorization from the authorities to operate as a bank.

(Reporting by Noe Torres; Editing by Stefanie Eschenbacher and Jonathan Oatis)

By Noe Torres