KYIV -- Ukraine's central bank has accused tycoon Ihor Kolomoyskiy of organizing an attack on it and spreading "lies" in the media to "create chaos" at the institution.

The National Bank of Ukraine (NBU) said in a November 27 statement that it had asked law enforcement to help prevent possible "illegal actions" by the oligarch toward its employees.

"A coordinated attack targeting the National Bank has been under way for several weeks in the form of spreading ordered speculation and lies in media, rallies in front of the NBU building by people who were paid to attend, and even an attempted forced entrance to the NBU by paid individuals," the bank said in a statement, adding that "this pressure on the National Bank is being imposed by the oligarch and former owner of PrivatBank, Ihor Kolomoyskiy, who owes $5.5 billion that was funneled out of PrivatBank."

PrivatBank was nationalized against Kolomoyskiy's will in 2016 as part of an International Monetary Fund (IMF)-backed clean-up of the country's financial system.

According to the NBU, rallies in front of its central Kyiv building were attended by workers of Kolomoyskiy-owned companies and organizations, "proving" that Kolomoyskiy was behind those rallies.

The statement says that the main goals of the campaign against the NBU are to discredit the bank and change its leadership to be able to influence the NBU's future.

The statement added that Kolomoyskiy hopes the actions will help him avoid liability and the need to return to the state the funds withdrawn from PrivatBank, as well as to meddle into Ukraine's cooperation with international financial institutions to influence their opinions regarding PrivatBank's nationalization.

Kolomoyskiy lost control over PrivatBank when the NBU took it over after it failed stress tests and was deemed to be undercapitalized. Two years later, an independent audit concluded that PrivatBank had conducted "large-scale and coordinated fraud" for at least 10 years before its takeover by the state.

U.S.-based corporate investigative firm Kroll and attorneys at AlixPartners also found a hole of at least $5.5 billion in the bank's balance sheet.

Kolomoyskiy has denied wrongdoing and maintains he is the rightful owner of the bank, which he has openly vowed to regain control over.

Kolomoyskiy faced investigations and government pressure in Ukraine during the presidency of Petro Poroshenko.

He lived in self-imposed exile for nearly two years and returned after President Volodymyr Zelenskiy's election in April. The two are reputed to be close.

Zelenskiy has denied that he will help Kolomoyskiy regain ownership of PrivatBank.