A lawyer for the family of Sergei Magnitsky, the lawyer whose death in 2009 sparked a crisis between Russia and the West, has been badly injured.
Russian media say Nikolai Gorokhov fell from the fourth floor when a rope snapped as he and others tried to lift a bath into his house near Moscow.
He was flown to hospital by helicopter, a medical source was quoted as saying.
However, British businessman Bill Browder, for whom Mr Magnitsky worked, said he had been “thrown”.
He did not give a source for his allegation.
According to a press release released by a website linked to Mr Browder, Law and Order in Russia, Mr Gorokhov was due to appear in an appeals court in Moscow on Wednesday to contest its refusal to investigate allegations of organised crime.
Mr Magnitsky died in prison after revealing alleged fraud by state officials.
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The incident involving Mr Gorokhov occurred in the town of Troitsk, south-west of Moscow. Russian media say several workmen were helping the lawyer at the time.
Life News, a Russian tabloid news site, published photos of a shattered bath lying on the ground by a block of flats.
Mr Magnitsky had been jailed after being accused of committing fraud himself. Supporters say his death in November 2009 was the result of a severe beating, but official records say he died of acute heart failure and toxic shock, caused by untreated pancreatitis.
Mr Magnitsky had acted as a legal adviser for London-based Hermitage Capital Management, founded by Mr Browder (formerly a US citizen), who was himself tried in absentia.
The Magnitsky affair soured relations between Moscow and Washington, casting a spotlight on corruption in Russia.
It led to US sanctions on a group of Russian officials, retaliation by Russia and the bizarre spectacle of Mr Magnitsky being put on trial posthumously.