VOA's Kenneth Schwartz contributed to this report.

KYIV — Ukrainian President Volodymyr Zelenskiy said Thursday there was "no blackmail" in his July phone call with U.S. President Donald Trump that is now at the center of an impeachment inquiry by the Democrat-led U.S. House of Representatives.

Zeleinskiy spoke about the phone call during a press conference Thursday with rotating groups of reporters in Kyiv, lasting a mind-boggling 10 hours.

Zelenskiy was repeatedly asked about the infamous July phone call where Trump seemed to imply he would block military aid to Ukraine unless it investigated Democratic presidential candidate Joe Biden and his son, Hunter. Hunter Biden was a board member of the Ukrainian energy firm Burisma.

"They blocked it [the military aid] even before we had the conversation. But we did not touch on it in our conversation," Zelenskiy said. "At that moment I did not know about it. I talked to the minister of defense afterwards and he said: We have a problem, they've blocked that money.' But when we were talking with Trump, this issue was not there at all. So there was no blackmail because it was not the subject of our conversation, at all."

Zelenskiy added it is up to the United States to resolve the issue.

FILE - President Donald Trump speaks during a ceremony in the Oval Office of the White House, Oct. 8, 2019.

In a tweet Thursday, Trump said the Ukrainian leader's latest comments to reporters "should immediately end the talk of impeachment."  

Meanwhile, House Democrats have subpoenaed Energy Secretary Rick Perry over his part in the Trump Ukraine scandal.

House Democrats say Perry may have "reinforced the stark message" Trump conveyed to Zelenskiy. Perry says his only interest was to get Trump to talk to the Ukrainians on energy matters.

According to a whistleblower complaint, and a rough transcript of the call released by the White House, Trump urged Zelenskiy to open an investigation into Biden.

Trump has described his conversation with Zelenskiy as a "perfect call" and the White House has said it is refusing to participate in the Democratic-led inquiry into whether the American president should be impeached.

The three main House committees conducting the impeachment inquiry released a set of text messages obtained from former U.S. envoy to Ukraine Kurt Volker, including one Volker sent to Zelenskiy aide Andrey Yermak saying, "We will nail down date for visit to Washington" if Zelenskiy "convinces Trump he will investigate."
Zelenskiy was elected in April on a platform of rooting out corruption. Now the Ukrainian leader is facing criticism over his own conduct, says political analyst Ilya Kusa of the Ukrainian Institute of the Future.
“It has become his first international diplomatic crisis. He allowed us to get involved in the American elections and this is not the thing that we should have done because we have plenty of our own problems and trying to get into this process – it’s too global, too big a game to play. And of course too risky because Ukraine here is just a gambling chip," Kusa said.

Trump has accused Biden of corruption, alleging that when he was vice president, he threatened to withhold loan guarantees to Ukraine unless the government stops investigating a gas company for which Biden's son, Hunter, held a seat.

FILE - Then-U.S. Vice President Joe Biden and his son Hunter Biden attend an NCAA basketball game between Georgetown University and Duke University in Washington, Jan. 30, 2010.

There is no evidence of any wrongdoing by Joe or Hunter Biden.

Former envoy to Ukraine Volker gave closed-door testimony to the House Intelligence, Foreign Affairs and Oversight committees last week.

The State Department blocked U.S. Ambassador to the European Union Gordon Sondland from giving planned voluntary testimony Tuesday, and it is uncertain if the committees will be able to go ahead with their scheduled Friday meeting with former Ambassador to Ukraine Marie Yovanovitch.

The White House calls the impeachment inquiry "unconstitutional" and demands the full House be allowed to vote on whether there should be an inquiry.

But there is no rule preventing the House from looking into allegations of illegal activity by a president before deciding whether to bring actual articles of impeachment to a vote.

Speaker of the House Nancy Pelosi called the White House letter "the latest attempt to cover up his (Trump's) betrayal of our democracy and to insist that the president is above the law."

She says Democrats would consider a refusal to cooperate more evidence of obstruction.