Russia's election commission has found flaws in papers submitted by candidate Boris Nadezhdin that could be used to keep him off the ballot paper in next month's presidential election, Nadezhdin said Monday.

The pro-peace campaigner has galvanised Russia's opposition in recent weeks with his surprise bid to run against President Vladimir Putin in the highly controlled presidential contest.

But he said Monday that a working group of Russia's Central Election Commission had thrown out more than 15 percent of signatures it checked from those he submitted backing his candidacy.

Candidates hoping to get on the ballot must submit signatures from 100,000 supporters. A check on their validity by the election commission must not find errors or discrepancies in more than five percent of them.

"The election commission working group reported a 15-percent error rate in the signatures I submitted on 31 January," Nadezhdin said in a post on social media on Monday.

That was based on an initial check of 60,000 of the signatures submitted.

Nadezhdin said he plans to contest the findings and his campaign staff said they had "two sleepless nights ahead" before a February 7 deadline when the commission will rule on whether he can stand.

An elections official said last week it had found the names of "dead souls" among the signatures submitted by Nadezhdin in what was seen as paving the way to block him from standing.

The Kremlin tightly controls all ballots inside Russia and has a track record of citing administrative errors to stop opposition candidates from registering their candidacy.

Putin is set to secure another six-year term in the March 15-17 vote, which would keep him in the Kremlin until at least 2030.

He has ruled Russia as president or prime minister since the final day of 1999.

Nadezhdin, a municipal councillor who criticises Russia's military offensive on Ukraine, says he is the only genuine opposition candidate trying to stand in the contest.