A Russian court on Monday ordered opposition leader Alexei Navalny and ally Lyubov Sobol to pay 88 million rubles ($1.4 million) in damages to a company controlled by a top Kremlin ally.
In February, Navalny's Anti-Corruption Fund (FBK) released an investigation criticising a school catering firm over the quality of its food.
Citing a former employee of the company, FBK said the firm was controlled by businessman Yevgeny Prigozhin, who is close to President Vladimir Putin and under US sanctions.
"So they poisoned children in schools and kindergartens," said Navalny, an anti-corruption campaigner who has emerged as Putin's most prominent critic.
"The cases of dysentery were documented. But it's us who should pay," Navalny said in an Instagram post on Monday.
Navalny's spokeswoman Kira Yarmysh said that he and Sobol -- a lawyer who was barred from running for Moscow parliament this year -- and the FBK should each pay roughly 29 million rubles to the Moskovsky Shkolnik firm.
The opposition fund was also ordered to retract the report.
Yarmysh said they would appeal the court ruling.
Authorities have been steadily ramping up pressure on Navalny and his supporters over the past few months.
The 43-year-old helped organise major protests against the government this past summer when tens of thousands took to the streets of Moscow to demand fair elections.
Authorities unleashed a brutal crackdown, sentencing several people to jail terms of between two and five years. Several more are in pre-trial detention.
Navalny also instructed supporters to vote strategically to block pro-Kremlin candidates in Moscow and regions after opposition politicians were barred from standing.
As a result, Kremlin allies suffered significant losses.
In August, investigators launched a money-laundering probe into Navalny's anti-corruption foundation, accusing it of taking money as donations that was procured illegally.
This month, FBK was declared a "foreign agent" and Navalny's offices have been raided repeatedly.