A former adviser to Ukrainian President Volodymyr Zelensky said it was made obvious to Ukrainian officials that President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE would communicate with them only if they agreed to discuss former Vice President Joe Biden Joe BidenFormer Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick Bloomberg rolls out M ad buy to boost Biden in Florida MORE’s son Hunter Biden, ABC News reported on Wednesday.

"Ukrainian officials were asking for a meeting with Trump for along time. As I remember, it was a clear fact that Trump wants to meet only if Biden case will be included," said Serhiy Leshchenko, an anti-corruption advocate and former member of Ukraine's parliament, told ABC. "This issue was raised many times. I know that Ukrainian officials understood."

Leshchenko, however, later disputed ABC's characterization of his remarks, saying he only learned of any quid pro quo arrangement with the White House through media reports.

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The White House on Wednesday released notes summarizing a call between the two leaders in which Trump encouraged Zelensky to collaborate with both his personal attorney Rudy Giuliani Rudy GiulianiThe Hill's Campaign Report: GOP set to ask SCOTUS to limit mail-in voting CIA found Putin 'probably directing' campaign against Biden: report Democrats fear Russia interference could spoil bid to retake Senate MORE and Attorney General William Barr Bill BarrFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Why a backdoor to encrypted data is detrimental to cybersecurity and data integrity FBI official who worked with Mueller raised doubts about Russia investigation MORE on investigating whether Joe Biden influenced the firing of then-Prosecutor General Viktor Shokin.

The call is the subject of a whistleblower complaint released to Congress on Wednesday, and it prompted House Speaker Nancy Pelosi Nancy PelosiDemocratic senator to party: 'A little message discipline wouldn't kill us' Overnight Health Care: New wave of COVID-19 cases builds in US | Florida to lift all coronavirus restrictions on restaurants, bars | Trump stirs questions with 0 drug coupon plan Overnight Defense: Appeals court revives House lawsuit against military funding for border wall | Dems push for limits on transferring military gear to police | Lawmakers ask for IG probe into Pentagon's use of COVID-19 funds MORE (D-Calif.) to announce the House would begin an impeachment inquiry Tuesday.

Leshchenko told ABC News that in Ukraine, the proposed investigation was encouraged by Shokin’s successor, Yuri Lutsenko, who Leshchenko said sought out Giuliani to seek protection from the U.S. because he was concerned Zelensky would dismiss him as prosecutor general.

"We understood that he was just trying to protect his position in the new administration using this scandal," Leshchenko said. "And he put Ukraine on this battlefield."

Ukrainian Deputy Interior Minister Anton Gerashchenko told ABC that to his knowledge, no request for an investigation had been made through formal channels.

“If there will be a request from the American side, we’ll look at it,” he said.

—Updated Friday at 11:09 a.m.