Russian lawmakers on Friday accused a fellow deputy of betraying national interests after he delivered a speech in the United States criticising President Vladimir Putin's crackdown on the opposition.
Dmitry Gudkov, 33, travelled to Washington in early March to give a speech at a forum organised by a pro-democracy group headed by Pavel Khodorkovsky, the son of the jailed oil tycoon Mikhail Khodorkovsky.
In the speech released by Gudkov, he lambasted "repressive methods of Putin and his minions" and called on the United States to help expose corrupt officials by providing information on their accounts in Western banks.
On Friday, the deputy speaker of the Russian lower house of parliament, the State Duma, said that representatives of all four Duma factions had lodged a complaint over Gudkov's speech with the ethics committee.
"Gudkov's speech amounts to an attack on our country's sovereignty," Sergei Zheleznyak said in comments posted on the website of the ruling party United Russia.
The ethics committee is scheduled to look at the complaint on Wednesday. Zheleznyak said the entire lower house would then address Gudkov's behaviour, indicating the deputy may lose his mandate.
Gudkov said he believed that Russian lawmakers were incensed by his call on the United States to help fight corruption in Russia.
"The deputies got scared because many of them have property in the States and their children study there," he told AFP.
The head of the Duma's ethics committee Vladimir Pekhtin resigned last month after opposition bloggers accused him of having US-based property worth over $2 million.
Dmitry Gudkov's father, Gennady Gudkov, who is a vocal member of the anti-Kremlin opposition, was expelled from the parliament in September over alleged conflicting business interests.
Both men were expelled from their left-leaning party, A Just Russia, earlier this week because of their opposition activities.
The opposition charges that the parliament lacks legitimacy because 2011 parliamentary elections were slanted in favour of the ruling party.
Since Putin's return to the Kremlin for a third term, the parliament has fast-tracked a number of controversial laws that critics say are designed to clamp down on civil society.