Silicon Valley tech firms are countering public perception that they provide the U.S. federal government access to users' personal information, according to a report by the Associated Press.

After sending an open letter addressed to the Obama administration that calls for transparency, Silicon Valley tech firms, including Apple and Facebook spoke aggressively against the federal government's surveillance methods that involves snooping into users' private information.

The tech industry suffered a backlash after former National Security Agency (NSA) analyst and contractor Edward Snowden revealed that the NSA is prying into the lives of web users using information collected from tech data centers, the report said.

As a result, tech firms like Apple Inc., Facebook Inc., Microsoft Corp., and Yahoo! Inc., have been very vocal about the federal government's surveillance of private citizens.

In his blog, Brad Smith, Microsoft's general counsel, warned that the U.S. federal government's online surveillance "threaten to seriously undermine confidence in the security and privacy of online communications."

"Indeed, government snooping potentially now constitutes an 'advanced persistent threat,' alongside sophisticated malware and cyber-attacks," he wrote.

Apart from the open letter published, tech firms have been crusading against the government by going to courts and Congress to force the government to make public the latter's online investigations. The crusade is the industry's attempt to show that the information it has given the federal government was under court order and has affected a small portion of their more than 1 billion users.

Tech firms recognize that the trust of its online users is at stake, meaning they could lose billions of dollars if users stop using their products and services. When companies like Google, Yahoo!, and Facebook collect personal data, they track the interest and habits of their users. They then use the data to tailor-fit advertising campaigns.

"The entire tech industry has been implicated and is now facing a global backlash," Daniel Castro, a senior analyst for the Information Technology and Innovation Foundation, a Washington D.C. think tank, told the Associated Press.