SAO PAULO- Brazil's Banco Bradesco SA BBDC4.SA will present an all-digital franchise this week called Next, marking the biggest campaign of a major bank in Latin America's top economy to go head-to-head with financial technology startups, or fintechs.

Targeting tech-savvy Brazilians aged 18 to 34, Bradesco is partnering with big brands such as Apple Inc AAPL.O , Uber Technologies Ltd and Microsoft Corp's MSFT.O Xbox to offer perks on plans that cost 20 reais to 40 reais ($6-12) per month.

In an interview, Mauricio Minas, Bradesco's vice president of technology, said the all-digital efficiency of Next allows it to offer lower rates than those charged at physical branches.

Still, he ruled out the idea of fighting fintech rivals by scrapping fees or offering the lowest possible interest rates.

"Those who have very low interest rates do not sustain themselves over time," said Minas. "Next will not be irrational with fees."

Bradesco's new initiative is just the latest example of how big Brazilian banks are being forced cut costs and innovate as they confront the threat of fast-growing fintechs.

Last week, Brazilian startup Nubank said it would expand from credit cards into digital accounts allowing users to make transfers, pay bills and earn more interest than an average savings account.

($1 = 3.24 reais)

(Reporting by Aluisio Alves; Writing by Alexandra Alper; Editing by Louise Heavens) ((Alexandra.Alper@thomsonreuters.com; 021-98186-5429; Reuters Messaging: alexandra.alper.thomsonreuters.com@reuters.net))