Officers of the United States' Federal Bureau of Investigation (FBI) are stationed at Ukraine's National Anti-Corruption Bureau (NABU) on a rotation basis and take no part in inquiries, Ukrainian Specialized Anti-Corruption Prosecutor Nazar Kholodnytsky said on the 1+1 channel on Sunday evening.

"The FBI is operating in Ukraine under a memorandum of mutual understanding," Kholodnytsky said.

He denied that the bureau was conducting a joint special operation with the FBI.

"FBI officers are being stationed at NABU on a rotation basis; they are giving advice, sharing practices and information, and may be helping expedite certain international requests, however the FBI officers are not investigating cases, they are not included in investigative task forces, and are not running round the city of Kyiv with pistols in their hands to detain any people," he said.

Ukrainian Prosecutor General Yuriy Lutsenko said on the 1+1 channel on December 3 that if NABU had conducted its operation at the State Migration Service together with the FBI that would be a breach of the law.