SAN FRANCISCO - WikiLeaks criticized Google Inc on Monday, alleging that the company waited 2-1/2 years to notify members of the anti-secrecy group that it had turned over their private emails and other information to the US government.

Lawyer for Julian Assange, Melinda Taylor, WikiLeaks journalists Kristinn Hrafnsson and Sarah Harrison and former Spanish judge Baltasar Garzon (L-R), director of legal team of WikiLeaks founder Julian Assange, pose with some documents before a news briefing at Geneva Press Club in Geneva, January 26, 2015. [Photo/Agencies]

In a letter to Google, lawyers representing WikiLeaks said they were "astonished and disturbed" by Google's actions relating to search warrants it received from federal law enforcement officials and asked for a full accounting of the information Google gave the government.

The revelation follows leaks by former National Security Agency contractor Edward Snowden detailing controversial US government surveillance practices and assurances from technology firms like Google that they would do their utmost to safeguard users' personal information.

"While it is too late for our clients to have the notice they should have had, they are still entitled to a list of Google's disclosures to the government and an explanation why Google waited more than two and a half years to provide any notice," read the letter from the Center for Constitutional Rights on behalf of WikiLeaks and addressed to Google Executive Chairman Eric Schmidt and General Counsel Kent Walker.

WikiLeaks, founded by Julian Assange, landed in the public spotlight in 2010 when it published a trove of classified government information, including leaked US diplomatic cables.

Google, whose online services include the world's No.1 Internet search engine as well as the popular Web email service Gmail, notified three members of WikiLeaks on December 23, 2014 that it had provided "all of their email content, subscriber information, metadata and other content" to law enforcement officials more than two years earlier, according to the letter.

Google provided the information in response to warrants for an investigation concerning espionage, conspiracy to commit espionage and the theft or conversion of property belonging to the US government, among other items, the letter said.

Google said in a statement on Monday that it has a policy of informing users about government requests "except in limited cases, like when we are gagged by a court order, which sadly happens quite frequently."

Google noted that it has pushed to unseal all the documents related to the investigation.

WikiLeak's letter drew a comparison to social media service Twitter Inc, which it praised for fighting the government in order to notify subscribers about such court orders.

The letter from WikiLeaks' lawyers asked Google to provide details about whether it had initiated any challenge to the search warrants before complying and whether it initiated any legal challenge to notify users about the warrants.