The bank announced the deal in a joint statement but did not disclose the financial details.

Fidor, an entirely online-based bank that prides itself on completing all of its services in under 60 seconds, will remain independent after the takeover, which will help it address a funding squeeze, its chief executive said.

For BPCE, France's second-largest banking group, the acquisition marks the move into digital services as more customers handle their business online.

"This operation constitutes a milestone in the acceleration of the digital transformation of our group," BPCE CEO Francois Perol said in a statement.

Fidor was founded in 2009, one of the first German fintech companies, and now has 120,000 customers.

"Our growth made us reach the limits of our capital resources," Fidor CEO and co-founder Matthias Kroener told Reuters, adding that the deal with BPCE allowed the company to reach the "next phase of growth".

The German lender recently partnered with German telecoms operator Telefonica Deutschland to offer an online bank account that pays out interest to customers in the form of mobile phone data usage rather than cash.

(Reporting by Tina Bellon and Alexander Huebner; Editing by Susan Fenton)