Apple has expressed opposition to a proposed U.K. surveillance law, saying threats to national security don’t justify weakening privacy and putting the data of hundreds of millions of users at risk. The company is leading a Silicon Valley challenge to the Investigatory Powers Bill, which attempts to strengthen the capabilities of law-enforcement agencies to investigate potential crimes or terrorist attacks. The bill would, among other things, give the government the ability to see the Internet browsing history of U.K. citizens.

Apple said the U.K. government already has access to an unprecedented amount of data. The company is particularly concerned the bill would weaken digital privacy tools such as encryption, creating vulnerabilities that will be exploited by sophisticated hackers and government spy agencies.

"The creation of back doors and intercept capabilities would weaken the protections built into Apple products and endanger all our customers," Apple said in an eight-page submission to the U.K. parliamentary committee considering the bill. "A key left under the doormat would not just be there for the good guys. The bad guys would find it too."

In response to the U.K. bill, Google, Facebook, Twitter, Yahoo and Microsoft also will be submitting evidence to the committee, the Financial Times reported, citing people familiar with the matter. The U.S. technology companies have been strengthening use of encryption technology following revelations by National Security Agency whistle-blower Edward Snowden of government spying in 2013.