Google joined Internet rights activists on Tuesday in a virtual protest aimed at getting US lawmakers to rein in online snooping.

The American Civil Liberties Union, Amnesty International, the Electronic Frontier Foundation and Yahoo-owned Tumblr also backed of an online protest called "The Day We Fight Back."

More than 100,000 emails were sent and 46,000 phone calls placed to members of the US Congress to oppose privacy "intrusion" by the National Security Agency, according to organizers.

"Winning this fight is going to require a broad coalition of individuals, organizations, and businesses, one that is coalescing around today's activism and will persist until we win the fight against mass suspicion-less surveillance," said David Segal, whose Internet freedom organization claims 1.5 million members.

A website called thedaywefightback.org provided simple tools to call or email US legislators, and even provided a script of what to say.

Participating websites were to provide links and other tactics to get visitors to barrage members of Congress with Twitter messages, Facebook posts, emails, or calls opposing US online spying.

Revelations about US surveillance practices at home and abroad have sparked an overdue debate about US surveillance, Google vice president of public policy Susan Molinari said.

"Google recognizes the very real threats that the US and other countries face, but we strongly believe that government surveillance programs should operate under a legal framework that is rule-bound, narrowly tailored, transparent, and subject to oversight," she said.

Protest backers hoped to harness the collective power of Internet users to advance a USA Freedom Act that would reform surveillance practices.

"By overwhelming every member of Congress's phone line, inbox, and Facebook and Twitter accounts with our demand to end government mass surveillance, we can deliver a message impossible to ignore," ACLU legislative counsel Michelle Richardson said.

Other events and gatherings were planned for Britain, Brazil, Canada, Colombia, Costa Rica and other countries, organizers said.

"American democracy has been turned on its head," said Linda Schade from the Defending Dissent Foundation.

"Rather than citizen oversight of a transparent and accountable government, we have government conducting secretive surveillance of every aspect of our lives. Something is very wrong and it is our civic duty and responsibility to act. Today is the day we fight back."

The events were a tribute to the late online activist Aaron Swartz, who helped organize protests to thwart the Stop Online Piracy Act and Protect IP Act in 2012.