One of Russian President Vladimir Putin's most vocal and influential parliamentary critics said Saturday that prosecutors had asked lawmakers to expel him so that he could be charged with business crimes.

Gennady Gudkov of the leftist A Just Russia party said he had received a copy of a letter the Prosecutor General's office circulated among groups in the pro-Kremlin legislature seeking a vote on his seat.

The claim came amid widening probes into allegedly suspect business activities that were first reported by Kremlin-controlled media after Gudkov helped lead the historic winter protests against Putin's rule.

"The letter says in part, and I quote 'it is essential that you consider prematurely terminating the powers of State Duma Deputy Gennady Vladimirovich Gudkov,'" Interfax quoted the lawmaker as saying.

There was no immediate comment from prosecutors.

Federal investigators have already spent weeks looking into a property deal Gudkov admits he was a part of in Bulgaria that resulted in a furious row between its partners and accusations of fraud.

But Gudkov insists he pulled out of all his conflicting business obligations by the time he joined parliament in 2001 and therefore broke no federal law.

Gudkov's ouster would rid parliament of one of Putin's strongest opponents - a 56-year-old who enjoys national recognition and therefore receives coverage from the main television channels despite his critical views.

Putin's allies in the ruling United Russia party suffered heavy losses in December parliamentary elections and now only control a slim majority that is helped by support from a small bloc led by the maverick Vladimir Zhirinovsky.

Gudkov's party had once also voted with the Kremlin.

But his prominent place in the front row of Moscow's largest demonstrations since the Soviet Union's fall forced other members of his the group to take a harder stance and start voting against Putin's policies.

The decision strips the Kremlin of a reliable majority at the very onset of Putin's third term and complicates his attempt to tighten his grip on Russia after a four-year absence as prime minister.

Some analysts believe that the Kremlin hopes to make the chamber more compliant by stripping Gudkov of his seat and launching criminal proceedings against him that could serve as a warning to other members of his party.

The Duma has tentatively scheduled a debate on Gudkov's status for Thursday - a move denounced as illegal by his party.

Russian law sets up a complicated procedure for stripping lawmakers of immunity from prosecution that requires at least two votes that come before and after a formal criminal review period.

But the Duma set its own procedures and has previously stripped critical lawmakers of their seats or right to speak without much debate.

Gudkov denounced the chief prosecutor's letter as "something that gives the Duma license to exact revenge against out of favor deputy."

The main case against Gudkov is built on allegations from a shadowy Bulgarian businessman who was recently released from jail named Ivaylo Zartov.

The small property developer told sate-controlled NTV television this summer that Gudkov was in fact a mafia boss who commanded unimaginable wealth. The accusation led to ruling party calls for a probe.

Gudkov for his part admits helping organize a Russian business group's loan for a proposal by Zartov to build townhouses in Bulgaria's Black Sea resort of Burgas.

[Image via Agence France-Presse]