State Duma Speaker Sergei Naryshkin has signed a decree officially terminating opposition lawmaker Gennady Gudkov's parliamentary powers, according to the Duma's press service.

Naryshkin reportedly signed the decree Friday night, after a majority in Russia's lower house voted to strip Gudkov, a deputy with the socialist party A Just Russia, of his mandate over alleged business activities. Engaging in business while serving as a parliament deputy is forbidden by Russian law.

Gudkov could face prosecution leading to jail time if convicted of illegal business dealings while serving in parliament.

The lawmaker's expulsion, only the second of a Duma member in Russia's post-Soviet history, came ahead of a mass rally set for central Moscow on Saturday against the twelve-year rule of President Vladimir Putin.

Both critics and Gudkov himself have slammed the vote as a politically-motivated move to punish a key Putin critic.