Ukrainian President Volodymyr Zelenskiy on Wednesday, May 20, called for an investigation of leaked audio that appeared to indicate Vice President Joe Biden linked U.S. aid to Ukraine prosecutor’s ouster.

The leaked audio was private phone calls between Biden and former Ukraine President Petro Poroshenko, in which Biden told Poroshenko that his country would receive U.S. aid once top prosecutor Viktor Shokin, who was investigating Ukrainian energy firms Burisma Holdings where Biden’s son, Hunter Biden, served on its board paying him tens of thousands of dollars per month despite limited relevant expertise, was replaced.

At a press conference in Ukraine, Zelenskiy said that the contents of the leaked conversations “might be perceived, qualified as high treason.” The recordings were released by Andriy Derkach, a member of Ukraine’s Parliament, according to The Washington Post

“It’s going to be critical for him to work quickly to repair the damage that Shokin did,” the man identified as Biden said in one clip. “And I’m a man of my word. And now that the new prosecutor general is in place, we’re ready to move forward to signing that new $1 billion loan guarantee. And I don’t know how you want to go about that … I’ll leave it to you to how you want it done and where you want it done.”

Shokin, who has been accused of corruption but he dismissed the allegations as a “smear campaign,” purportedly has said under oath that he had opened a probe concerning Hunter Biden’s role at Burisma when he was ousted, reported the Fox News.

However, Poroshenko said in the recordings he had “no information” that Shokin had done “something wrong.”

“Yesterday I met with General Prosecutor Shokin, and despite of the fact that we didn’t have any corruption charges, we don’t have any information about him doing something wrong, I specially asked him—no, it was day [sic] before yesterday—I specially asked him to resign in his position as a state person,” Poroshenko apparently said on Feb. 18, 2016, according to Derkach’s clip. “And one hour ago he bring [sic] me the written statement of his resignation. And this is my second step for keeping my promises.“

“I agree,” Biden responded.

Biden previously acknowledged on camera two years after leaving office that he successfully pressured Ukraine to fire Shokin in 2016. But, Biden claimed that he did that with then-President Barack Obama’s approval over concerns of corruption.

Biden said he had threatened to withhold $1 billion in critical U.S. aid if Shokin was not fired. “Well, son of a [expletive], he got fired,” Biden said.

Former National Security Adviser Susan Rice confirmed that Biden applied that pressure on Ukraine was per the request of Obama. 

“Joe Biden was doing what he asked to do by the president of the United States consistent with serving our policy interest,” Rice told “CBS This Morning” co-host Tony Dokoupil. “President Trump on the one hand is asking Ukraine for a favor that benefits him personally and politically. Joe Biden on behalf of President Obama of the United States and the Western world, was asking and pushing for the removal of somebody on behalf of our policy, on behalf of our national interest.”

Last summer, President Trump suggested during a phone call with Zelenskiy that Ukraine look into Biden’s boast about firing Shokin, after Zelenskiy first mentioned Ukraine’s corruption issues. The president’s request came after millions in U.S. military aid to Ukraine had been frozen, which Democrats cited as a quid pro quo arrangement. They then accused the president of abuse of power to investigate political opponent for personal gain and led an impeachment inquiry against him. President Trump was acquitted in the Senate in February.