Police said the breach was a matter of online security "worldwide", warned that the hack had already led to a series of "spin-off crimes and further victimisation" by people claiming to provide access to the leaked data.

Toronto Police has set up a bespoke Twitter account to handle the investigation, where anyone with leads or who thinks they are a victim can contact officers. More than 33 million people are thought to be affected.

Acting staff superintendent Bryce Evans said Toronto Police had "a good working relationship" on the matter with the FBI and Homeland Security in the US.

At a press conference in Toronto, officers said the company behind Ashley Madison was offering a $500,000 reward for anyone who could provide information "that leads to the identification, arrest and prosecution of the person or persons responsible for the leak of the Ashley Madison database".