As such, technology giants urged the US to take the lead and make reforms that ensure that government surveillance efforts are clearly restricted by law, proportionate to the risks, transparent and subject to independent oversight.

 "We are focused on keeping user's data secure ? deploying the latest encryption technology to prevent unauthorized surveillance on our networks and by pushing back on government requests to ensure that they are legal and reasonable in scope," the letter said.

 It said US surveillance programs shouldn't keep American tech companies from operating internationally, including in countries that oppose US access to their citizens' data.

"Protecting the privacy of our users is incredibly important to Yahoo. Recent revelations about government surveillance activities have shaken the trust of our users, and it is time for the United States government to act to restore the confidence of citizens around the world," said Yahoo CEO Marissa Mayer.

Read Also: After Facebook, Now Access Twitter On Mobiles Without Internet  and 6 Sailfish Features That Android And iOS Lack