The Kremlin-linked businessman Yevgeny Prigozhin has vowed to ruin Russian opposition leader Alexei Navalny, who is in a coma in a Berlin hospital, with a court-ordered penalty of around $1.2 million.
Prigozhin is nicknamed "President Vladimir Putin's chef" because his company Concord has done catering for the Kremlin.
Media reports have said he funds Wagner, a private army of mercenaries, which he denies.
Navalny, a 44-year-old lawyer and anti-corruption campaigner who is one of Putin's fiercest opponents, is being treated at Berlin's Charite hospital after falling ill on a flight in Siberia. Tests by German medics indicated poisoning by cholinesterase inhibitors, which are found in nerve agents.
Concord's press service in a statement on social media on Tuesday evening quoted Prigozhin as saying he intended to enforce a court decision last year that Navalny and his associates must pay him almost 88 million rubles ($1.2 million at the current exchange rate) in damages over a video report.
"I intend to strip this group of unscrupulous people of their clothes and shoes," Prigozhin was quoted as saying after paying off the company directly named in the court case, meaning the payment would go to him directly.
Prigozhin said that "if comrade Navalny kicks the bucket, I personally don't intend to persecute him in this world.
"I'll put this off for an indefinite time and then I'll compensate myself to my pleasure."
If Navalny survives, Prigozhin said he would be liable "according to the full severity of Russian law."
A court in October last year ordered that Navalny, his associate Lyubov Sobol and the Anti-Corruption Foundation he founded must jointly pay almost 88 million rubles to the Moskovsky Shkolnik (Moscow schoolboy) company that makes school dinners.
The company has been linked to Prigozhin in media reports. He denies owning it.
The case concerned a video investigation by the foundation that accused the company of monopolising the market and alleged its food was bad quality and made children ill.
Navalny in July formally closed the foundation in a move to avoid paying its share of the court-ordered penalty.
Its director Ivan Zhdanov in a message to supporters on Wednesday suggested that Navalny could have been poisoned over one of the foundation's investigations.