Deutsche Bank CEO John Cryan speaks during the bank's annual general meeting in Frankfurt, Germany May 18, 2017. Reuters/Ralph Orlowski John Cryan, the chief executive of Deutsche Bank has warned that a "big number" of staff at the company will ultimately be replaced by robots and other forms of technology as the firm embraces a "revolutionary spirit" going forwards.

Speaking at the Handelsblatt banking conference in Frankfurt on Wednesday morning, Cryan told the audience that the era of accountants and bankers acting like "abacusses" is coming to an end.

"In our banks we have people behaving like robots doing mechanical things, tomorrow we’re going to have robots behaving like people," he said, according to a report from the Financial Times.

"We have to find new ways of employing people and maybe people need to find new ways of spending their time... The truthful answer is we won’t need as many people."

Cryan did not give any concrete indication of how many staff may eventually be replaced by technological advances, but said it would be a "big number." Deutsche Bank currently employs around 100,000 staff globally.

"We need to admit that what we had is nice but it’s not necessarily for the future," he added. "We need more revolutionary spirit."

Technological advances in banking and the wider jobs market mean that many believe that a large number of more straightforward jobs, such as data entry, will soon be replaced by automation.

A 2016 report from the World Economic Forum argued that automation will lead to a net loss of over 5 million jobs in 15 major developed and emerging economies by 2020.

Certain banking roles are already being impacted with the rise of so-called "robo-advisors" which are able to give financial advice to customers without relying on an actual person.

HSBC is one major bank to roll out robo-advice, launching a service in June that "will use data and algorithms to deliver tailored advice and will make personal recommendations based on an individual’s unique circumstances."

During the same speak, Cryan said that Frankfurt — the location of Deutsche Bank's headquarters — must invest heavily in infrastructure if it is to take over from London as Europe's financial hub after Brexit.