In this photo illustration, a visual representation of a digital cryptocurrency coin sits on display in front of a Facebook logo on June 17, 2019 in Paris, France.

Banks must evolve or risk being "left behind" as big tech companies shake up the financial system, according to new research from the International Monetary Fund (IMF).

In a paper published Monday titled "The Rise of Digital Money," IMF authors Tobias Adrian and Tommaso Mancini-Griffoli said the two most common forms of money today, cash and bank deposits, will "face tough competition and could even be surpassed."

But banks are "unlikely to disappear" as they face growing threats from big tech companies and fintech start-ups, the paper said.

"Some will be left behind no doubt," the authors wrote. "Others will evolve, but must do so quickly."

The research was published as central bankers and policymakers debate the role that tech companies and digital currencies will play in the banking and payments system.