Eight major tech giants have called for tighter controls on government surveillance, joining forces to argue there should be reforms in the way the United States snoops on people.

The companies, including Google, Facebook and Twitter, issued an open letter to U.S. President Barack Obama, saying that while governments have a duty to protect citizens, recent revelations have “highlighted the urgent need to reform government surveillance practices worldwide.”

The letter published Monday said: “The balance in many countries has tipped too far in favor of the state and away from the rights of the individual – rights that are enshrined in our Constitution.”

The letter follow revelations by former National Security Agency contractor Edward Snowden, who leaked details of the secret programs that critics say violate privacy rights.

“We understand that governments have a duty to protect their citizens. But this summer’s revelations highlighted the urgent need to reform government surveillance practices worldwide,” the companies wrote in a statement. “The balance in many countries has tipped too far in favor of the state and away from the rights of the individual.”

Documents released by former Snowden show that the agency gained access to the customer accounts of technology companies, circumvented encryption, and tapped fiber- optic cables as part of its surveillance programs, according to reports in the Washington Post, the New York Times and Guardian newspapers. The companies have responded by boosting encryption and pushing back on government requests for information.

Signatories to the statement are AOL Inc., Apple, Google, Facebook Inc., LinkedIn Corp., Microsoft Corp., Twitter Inc. and Yahoo! Inc.

Obama plans to propose curbs on the NSA to guard against unwarranted snooping, he said in an interview broadcast on MSNBC last week.

Encryption Steps

The joint statement from the eight companies comes after some of them have separately announced steps to expand use of encryption to protect customer information.

Microsoft last week said it shares concerns of its customers about government surveillance of the Internet.

“People won’t use technology they don’t trust,” Brad Smith, general counsel and executive vice president, legal and corporate affairs, at Redmond, Washington-based Microsoft, said in a statement. “Governments have put this trust at risk, and governments need to help restore it.”

Microsoft said it will step up its legal efforts to protect private data and make its software code more transparent so customers can reassure themselves Microsoft’s products don’t contain “back doors” allowing access to their information.

Yahoo, Twitter and Google have said they’ll beef up security. The Sunnyvale, California-based Yahoo said in November it will encrypt all information that flows between its data centers and will also let users encrypt data to and from the company by the end of the first quarter of 2014.

“Recent revelations about government surveillance activities have shaken the trust of our users,” Marissa Mayer, chief executive officer of Yahoo, said in the joint statement. “And it is time for the U.S. government to act to restore the confidence of citizens around the world.”