NSA whistleblower Edward Snowden has called on president Vladimir Putin not to approve a law that will require phone companies to store user content for six months.
On Friday Russia's lower house, the State Duma, voted to adopt a raft of new anti-terror laws, which will introduce far broader data-retention requirements targeting online and mobile communications in Russia.
Snowden, who was granted asylum by Russia in 2013, responded by tweeting that the new "Big Brother law" was an "unworkable, unjustifiable violation" of Russian citizens' rights, and called on Putin not to sign it into force.
Russian mobile phone companies will be required to store the content of all calls and text messages for six months, and retain call and message metadata for three years, according to Russian news agency TASS.
Internet service providers will also need to store users' personal data for one year.
"Mass surveillance doesn't work. This bill will take money and liberty from every Russian without improving safety. It should not be signed," Snowden wrote in a further appeal.
He also called the law dangerous and impractical due to the massive cost of storing user content. Russia's largest mobile phone operator MTS has estimated the cost of storing actual content for six months would be $33.8bn, according to The Washington Times.
Snowden has advocated a greater use of encryption by end users, but Russian's new law would also undermine that.
According to Latvian-based Russian news site Meduza, providers of online service such as messaging apps or social networks would face fines of up to $15,000 for not cooperating with a request from Russian intelligence to decrypt messages.
Putin is expected to sign the anti-terror measures into law, which were adopted as a response to the bombing of a Russian passenger plane over Egypt in October, The Guardian reported.
The law also raises the maximum punishment from four years to eight years in prison, while the penalty for encouraging mass disturbances will be five to 10 years in prison. Anyone who approves of terrorism on the internet could face up to seven years' prison.