Moscow (AFP) - Russians who refuse to take down online information that has been judged "false" by a court could be sentenced to up to a year in prison under a bill approved by MPs Tuesday in a key second reading.

Deputies in parliament's lower house voted to approve the measure that would apply to individuals on social media as well as to those working for media groups.

Senators and President Vladimir Putin still have to sign off on the bill following a formal third reading in parliament.

The law comes in the context of an ongoing crackdown on internet freedoms in Russia, where social media remains one of the few places the opposition can organise.

Those who break the rules outlined in the bill could also be subject to a 50,000-ruble ($740, 630-euro) fine, according to an approved text distributed on the judicial site pravo.ru.

Russia has in recent years increasingly criminalised online content, frequently jailing people for sharing or publishing information deemed extremist or illegal, including for calls for opposition protests and jokes deemed offensive to particular social groups.

The law currently forbids the sharing of content judged extremist, though rights groups say this label is also applied to opposition material.

"This new law, if it is adopted, will constitute a new attack on freedom of expression in Russia," Agora International Human Rights Group lawyer Irina Khrunova told AFP.

She said the move would target the likes of Alexei Navalny, the opposition leader and blogger who has used sites like Youtube to diffuse investigations into corruption among top officials.