Messaging apps like WhatsApp and iMessage would be forced to hand over the contents of encrypted messages under laws being proposed by the Australian government.

The Australian Prime Minister Malcolm Turnbull unveiled the new laws on Friday, saying they had been modelled on Britain's Investigatory Powers Act, which requires companies to decrypt communications in some circumstances.

However, he generated controversy when challenged on whether it was possible to fully crack down on encryption, saying that the laws of Australia override the laws of mathematics that govern how encryption work.