Apple has raised concerns about British plans to give security agencies extra online surveillance powers, saying a planned law could weaken the security of personal data for millions of people.
Britain unveiled proposals for sweeping new powers last month, including the right to find out which websites people visit.
The UK said these were needed to keep the country safe from criminals, fraudsters and militants.
Critics say the Investigatory Powers Bill gives UK spies powers beyond those available in other Western countries, including the US, and it is an assault on freedoms.
Apple said it was opposed to proposals in the bill that would weaken encryption, such as the explicit obligation on service providers to help intercept data and hack suspects' devices.
The California-based company uses end-to-end encryption on its FaceTime and iMessage services.
It said the best way to protect against increasingly sophisticated hacking schemes and cyber attacks was by putting into place increasingly stronger - not weaker - encryption.
"We believe it is wrong to weaken security for hundreds of illions of law-abiding customers so that it will also be weaker or the very few who pose a threat," the iPhone maker said.
"In this rapidly evolving cyber-threat environment,companies should remain free to implement strong encryption to rotect customers," it added.
As well as being able to carry out bulk interception of communications data, the bill would also allow the security services to perform "equipment interference", whereby spies take over computers or smartphones to access their data.
In its submission to the draft bill, Apple criticised any such requirement to create "backdoors" and intercept capabilities that could weaken the protections built into Apple products.
"A key left under the doormat would not just be there for the good guys," it said. "The bad guys would find it too."
Apple also said the proposals would attempt to force non-UK companies to take actions that violate the laws of their home countries, and would likely be the catalysts for other countries to enact similar legislation.