He said the blockchain "is an opportunity for banks to learn together about something that could have a very significant impact on our business in future years. It could be a virtual banking system."

Other banks are also investigating how the blockchain might be employed. Westpac chief executive Brian Hartzer​ said last month the development of the blockchain "will certainly have a very interesting and potentially disruptive impact on financial services". Westpac and CBA are also conducting trials with Ripple Labs to develop blockchain-like technology to allow banks to send information to each other.

Development of the blockchain has been one of the hottest topics at the SIBOS 2015 payments conference in Singapore this week, which is being attended by 8000 delegates.

Despite their enthusiasm for the blockchain, banks appear less supportive of bitcoin start-ups, with the competition watchdog considering an inquiry into the actions of banks for shutting down accounts of local bitcoin operators.

In a lunchtime speech to the Australia Israel Chamber of Commerce on Wednesday, Mr Thorburn also said NAB would put more funding into NAB Ventures, an innovation fund seeded with $50 million in July to invest in potentially disruptive businesses. He added the fund was not established to make a profit. "We are doing it to learn. It is equity capital at risk so we can learn faster to protect the core, grow our business and serve our clients better."