KYIV -- The U.S. State Department has denied an explosive claim by Ukrainian Prosecutor-General Yuriy Lutsenko that U.S. Ambassador to Kyiv Marie Yovanovitch gave him "a list of people whom we should not prosecute" during their first in-person meeting.

"The allegations by the Ukrainian prosecutor-general are not true and are intended to tarnish the reputation of Ambassador Yovanovitch," a State Department spokesperson told RFE/RL in e-mailed comments on March 21.

"Such attacks redouble our resolve to help Ukraine win the struggle against corruption," the spokesperson added.

Lutsenko did not say when the purported meeting with Yovanovitch took place. She was nominated to be ambassador by President Barack Obama in May 2016 and was sworn in in August of the same year.

The back and forth comes less than two weeks ahead of a Ukrainian presidential election in which challengers have sought to paint incumbent Petro Poroshenko as failing to combat corruption and abuses of power since taking office in mid-2014.

"The statement of Ukraine's prosecutor-general does not correspond to reality and is meant to weaken the reputation of Ambassador Yovanovitch," the State Department said.

Lutsenko's assertion came in an interview broadcast by The Hill's TV arm on March 20.

Lutskenko also reportedly told The Hill's John Solomon that Ukrainian authorities would "launch a criminal investigation" into whether Ukrainians sought to interfere in the U.S. election in 2016.

The question of Kyiv's actions in the run-up to Donald Trump's election as president in 2016 took on added significance with former Trump campaign manager Paul Manafort's U.S. prosecution for crimes connected with advisory work he did in Ukraine.

On March 20, Trump cited Solomon in a tweet repeating the allegation that Ukrainians had tried to "help" his Democratic opponent, Hillary Clinton, in 2016.

Poroshenko's administration was caught off-guard by Trump's election two years ago and pivoted abruptly to downplay perceived criticisms from Ukrainian officials of Trump during the campaign.

Kyiv has tried hard to maintain Western diplomatic and financial support as a simmering conflict continues in eastern Ukraine against Russia-backed separatists.

Lutsenko, a former interior minister who served jail time for charges that he and European officials described as politically motivated before a presidential pardon freed him in 2013, has served as an adviser to Poroshenko and is widely seen as the president's staunch political ally.

He was named prosecutor-general in 2016 despite having no law degree -- forcing parliament to amend legislation before approving his nomination.

He has since faced repeated calls from critics for his dismissal, and even announced his resignation as recently as November 2018.

In the halls of Ukraine's parliament after the reports of Lutsenko's comments about the U.S. ambassador, deputy speaker Oksana Syroyid said Poroshenko should either receive written, documented confirmation backing up the prosecutor-general's claim or fire Lutsenko.

"President Poroshenko this morning can only have [one of] two documents: either one substantiating the claim of Prosecutor-General Lutsenko or his submission to parliament that Lutsenko be dismissed as Ukraine's prosecutor-general," she said.

Lutsenko told Hill.TV that "from the first meeting with the U.S. ambassador in Kyiv, [Yovanovitch] gave me a list of people whom we should not prosecute," adding that such a thing was "inadmissible."

The State Department spokesperson said that "such allegations only serve the corrupt."

"The United States is committed to engaging with our partners in Ukraine, including on efforts to roll back the persistent corruption that continues to threaten Ukraine's national security, prosperity, and democratic development," the spokesperson continued. "Where there is a lack of political will on Ukraine's part, such as by the prosecutor-general's office, we exercise our fiduciary responsibility to the U.S. taxpayer and move assistance funds to where they can make a positive difference."

Yovanovitch in a recent speech was blunt in her criticism of Kyiv's anticorruption efforts, one of the key criteria for billions of dollars in lending from international institutions since the eastern Ukrainian conflict broke out in early 2014.

Yovanovitch also said that the chief of Ukraine's Special Anti-Corruption Prosecutor's Office, Nazar Kholodnytskiy, should be replaced to ensure the integrity of the anti-corruption institutions.

Kholodnytskiy has been embroiled in a corruption scandal over allegations that he helped officials suspected of corruption evade prosecution.

The war of words between Lutsenko and the United States adds to a politically charged environment in the run-up to next week's presidential vote in Ukraine.

Polls consistently show Poroshenko trailing comic and television personality Volodymyr Zelenskiy and neck-and-neck with former Prime Minister Yulia Tymoshenko ahead of the March 31 vote, which will go to a two-candidate runoff in April if no one surpasses 50 percent.