US politicians warned Facebook and Apple would face legislation compelling them to offer ways for police to access encrypted devices and data if they don’t develop such methods themselves.

During a congressional hearing, Senator Lindsey Graham reiterated claims encryption offers a “safe haven” for criminal activity and expressed frustration the issue had not yet been addressed.

“This time next year, if we haven’t found a way that you can live with, we will impose our will on you,” he said.

The threat comes more than a year after US, UK, Canada, Australia and New Zealand governments warned of potential action on the issue.

During the hearing, New York district attorney Cyrus Vance argued encryption had made it harder for police to retrieve information from mobile devices during investigations, noting the proportion of “locked” Apple devices had risen from 60 per cent in 2014 to 82 per cent in 2019.

He said tech companies had damaged the justice system with legislation “ensuring lawful access” the only solution.

But Erik Neuenschwander, director of user privacy at Apple, noted enabling access for police would also make it easier “for the bad guys to break in”, while Facebook Messenger product management director for privacy and integrity Jay Sullivan noted non-domestic companies would offer encryption services if US players do not.