Anti-corruption officers have accused Yulia Tymoshenko, the former prime minister of Ukraine, of bribery after raiding her party's offices in Kyiv on Wednesday.
It comes as Ukraine's leader, Volodymyr Zelenskyy, continues a widespread crackdown on corruption.
Ms Tymoshenko, who denies the allegations, is a high-profile opposition figure who led the country's Orange Revolution in 2005 and served as prime minister from 2007 to 2010.
She currently leads the Fatherland Party, which forms part of the opposition.
On Wednesday, local time, Ms Tymoshenko confirmed authorities from National Anti-Corruption Bureau (NABU) and Specialised Anti-Corruption Prosecutors Office (SAPU) raided her party's Kyiv headquarters.
She claimed 30 agents were "armed to the teeth" during the search.
"These 'urgent investigative actions' lasted all night and have nothing to do with law or justice," she wrote in a long social media post, in which she repeated denials of any wrongdoing.
"Without presenting any documents, [officers] effectively seized the building and took staff hostage."
The former prime minister also claimed the watchdogs' investigation was politically motivated.
"I categorically reject all these absurd accusations. It seems the elections are much closer than they seemed. And someone has decided to start a purge of political competitors," she wrote in the post.
Although Ms Tymoshenko did not mention whether she had been indicted, a densely-worded statement on NABU's website said a senior parliamentarian had been charged as part of the bribery investigation, describing it as a scheme that "offered undue benefits to MPs for proper voting".
"NABU exposed in December 2025 [that] several lawmakers were receiving unlawful benefits for proper voting on draft laws, the suspect started negotiations with certain MPs about unlawful benefits in exchange for loyal behaviour during voting," the statement read.
It went on to claim the bribery was systematic and that the suspect gave politicians specific instructions on how to vote in return for the "benefits".
Below the online statement, NABU published a pixelated photo of a woman, who appears to have the same distinct braided hairstyle Ms Tymoshenko sports.
The woman in the photo is sitting behind four small piles of cash.
The raid is the latest in a string of corruption sagas in war-torn Ukraine, a country with a long history of endemic graft.
Late last year, several close associates of Mr Zelenskyy were embroiled in a major scam involving the nation's troubled energy industry.
NABU alleged numerous senior politicians made millions through illegal kickbacks on contracts connected to a state-owned power company, all while Ukraine's residents suffered through regular blackouts during the country's bitter winter.
Mr Zelenskyy's chief of staff, Andriy Yermak resigned weeks after news of the scandal emerged, but has denied any wrongdoing.
The government was also widely criticised for attempting to wind back the powers of the anti-corruption agencies last year — a policy it backed away from after it sparked massive protests across Ukraine.
Despite being a frequent critic of Mr Zelenskyy, Ms Tymoshenko supported moves to dilute the powers of the watchdogs.
The ABC has spoken to Ukrainians who are increasingly frustrated with the allegations of politicians benefiting from crooked deals.
While elections in Ukraine are banned under the country's martial law, which has been in place since Russia launched its full-scale invasion in February 2022, Mr Zelenskyy has said he will hold an election if western allies can provide security guarantees.
