KIEV (Reuters) - Ukrainian President Volodymyr Zelenskiy said on Thursday he would be ready to open a probe into any Ukrainian interference in the 2016 U.S. presidential election and into the company where former Vice President Joe Biden’s son was a board member.

Ukraine has been unwillingly drawn into a political battle in Washington between President Donald Trump and his Democrat opponents over allegations that Trump used U.S. military aid as leverage to pressure Zelenskiy to open investigations.

Zelenskiy told reporters that Trump did not seek to blackmail him during a phone call in July or a meeting in September.

The U.S. House of Representatives has launched an impeachment inquiry against Trump, focused on whether he used congressionally approved aid to Ukraine as leverage to pressure Zelenskiy to investigate Biden, one of Trump’s main Democratic rivals as he seeks re-election in 2020.

Trump has made allegations, without evidence, that Biden engaged in improper dealings in Ukraine. Biden’s son Hunter was on the board of Ukrainian gas company Burisma. Trump’s personal attorney Rudolph Giuliani also alleges some officials in Ukraine conspired to help Trump’s Democratic challenger Hillary Clinton.

Zelenskiy said he was open to a joint investigation into Burisma and the 2016 U.S. election but stressed Ukraine was an independent country with independent law enforcement agencies whose work he had no right to influence.

“We are ready and I have already said this, if there would be a joint investigation and a joint commission of general prosecutors regarding the Burisma case, we are ready,” he told reporters. “And we are ready to investigate interference in the election from the Ukrainian side, if it took place. Because there is really much information on this out there. But it has to be confirmed.”

Ukraine’s new top prosecutor said last week he would review 15 previous investigations related to the founder of Burisma but also said he was not aware of any evidence of wrongdoing by Hunter Biden.

NO BLACKMAIL

Trump froze nearly $400 million in U.S. military assistance to Ukraine shortly before speaking to Zelenskiy, prompting accusations from Democrats that he had misused U.S. foreign policy for personal gain.

Trump has denied wrongdoing and defended the call as “perfect,” and many of his fellow Republicans have blasted the impeachment investigation as blatant partisan politics.

Zelenskiy said he had not known that U.S. military aid to Ukraine had been blocked at the time of the July call. Having been made aware of this by his defense minister later, he raised the issue during a separate meeting in September in Poland with Vice President Mike Pence.

Zelenskiy told reporters that his aim in having a phone call with Trump was to arrange a subsequent meeting and that he had asked the White House to change its rhetoric on Ukraine.

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“There was no blackmail. This was not the subject of our conversation,” Zelenskiy said about his call with Trump, speaking to reporters in a day-long series of televised briefings with the press, held at a Kiev food court.

Zelenskiy said there were no conditions attached to him meeting Trump, including whether he should investigate the activities of Joe Biden’s son Hunter at Burisma.

The White House published its summary of the call between Zelenskiy and Trump in September. Asked whether the Ukrainian version matched up to the U.S. one, Zelenskiy said: “I didn’t even check, but I think that it matches completely.”

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Zelenskiy said he was not willing to publish Ukraine’s record of the conversation.

Biden for the first time on Wednesday made a direct call for Trump’s impeachment. Trump meanwhile continued to paint the probe as a partisan smear and accused the U.S. intelligence officer who filed the whistleblower complaint that sparked the impeachment row of having political motives.

Zelenskiy said he had no desire to interfere in the U.S. election.

Zelenskiy said he had been made aware by his defense minister that Washington had frozen military aid to Ukraine.

He raised the issue at a meeting with Pence in Warsaw when they met at a commemoration to mark the 80th anniversary of the start of the Second World War.

“I told him ... please help to resolve it,” Zelenskiy recalled asking Pence. “And after our meeting America unblocked the aid.”