KYIV, Ukraine -- Ukraine's president insisted Thursday that he faced "no blackmail" from U.S. President Donald Trump in their phone call that helped spark an impeachment inquiry, distancing himself from the U.S. political drama and trying to claw back his own credibility.

Volodymyr Zelenskiy said for the first time that his country will "happily" investigate the conspiracy theory pushed by Trump that it was Ukrainians, not Russians, who interfered in the 2016 U.S. presidential election. And he encouraged U.S. and Ukrainian prosecutors to discuss investigating a gas company linked to the son of Trump's Democratic rival Joe Biden.

But Zelenskiy insisted he's not Trump's puppet and his moves appeared to be an attempt to put an end to questions dogging the Ukrainian president since details of his July 25 call with Trump emerged. He said U.S. officials have presented zero evidence of Ukraine's interference in 2016, but it's in his country's interests to find out once and for all what happened.

In an all-day "media marathon" held in a Kyiv food court, Ukraine's president played down suggestions that Trump pressured him in exchange for U.S. military aid to help Ukraine battle Russian-backed separatists. Congressional Democrats believe Trump was holding up the aid to use as leverage to pressure Ukraine and advance his domestic political interests.

Responding to questions from The Associated Press, Zelenskiy said he only learned after their phone call that the U.S. had blocked hundreds of millions of dollars in military aid to Ukraine.

"There was no blackmail," he said.

"We are not servants. We are an independent country."

Zelenskiy invited U.S. and Ukrainian prosecutors to co-operate on an eventual investigation into the Bidens, but insisted he would not interfere.

"I don't want to be pulled into this because I understand that my words could impact the elections of the American people," he said.

Trump has said the United States has an "absolute right" to ask foreign leaders to investigate corruption cases, though no one has produced evidence of criminal wrongdoing by the former U.S. vice-president or his son.

Trump also has pushed a long-discredited theory about Ukrainian interference in support of the Democrats in 2016, an attempt to cast doubt on Russia's role in the 2016 hacking of the Democratic National Committee. The theory contends, without evidence, that the DNC hack was based on fabricated computer records and designed to cast blame on Russia but was initiated from Ukraine.

Zelenskiy said Thursday that Ukraine would investigate the theory because otherwise we "can't say yes or no" as to whether there was any such interference.

During his July 25 call with Zelenskiy, Trump mentioned CrowdStrike, a security firm hired by the DNC that detected the hack. CrowdStrike has also worked for the Republicans. Trump has claimed the company was based in Ukraine, but it is based in the U.S. and company co-founder Dmitri Alperovitch is a Russian-born U.S. citizen.

The July call is central to the impeachment inquiry, and embarrassed Zelenskiy because it showed him as eager to please Trump and critical of European partners whose support he needs to strengthen Ukraine's economy and to end the conflict with Russia.

Zelenskiy said it was "wrong" of the White House to publish a rough transcript of the call -- and said he will not publish the Ukrainian transcript. He said he "didn't even check" whether the Ukrainian transcript of the July call is the same as that of the White House, but says "I think they match."

Zelenskiy appears to be playing to both U.S. political camps to ensure Ukraine has continued support no matter who wins the presidential election next year.

Zelenskiy said he thought the call would lead to an in-person meeting with Trump, and wanted the American leader to come to Ukraine. Zelenskiy said the "key question" for him was to try to persuade the White House to "change its rhetoric" about Ukraine as a corrupt and untrustworthy country.

Trump said the military aid was frozen because of concerns about corruption in Ukraine, but the move prompted congressional outcry and the money was released in September.

Asked what Ukraine did to persuade the U.S. to release the aid, Zelenskiy said: "We have many diplomatic contacts. And in case we need to find a solution to questions of this level, questions about our country's security, we use all our powerful possibilities." He didn't elaborate.

A TV and film comedian, Zelenskiy overwhelmingly won the presidency in April on promises to fight corruption and end the five-year conflict with Moscow-backed separatists in eastern Ukraine. He's treading carefully to ensure continued support from the U.S. while trying to make peace with powerful neighbour Russia.

Most of the questions at Thursday's unusual media event related to the Russia conflict or Ukraine's economic troubles.

Zelenskiy also joked about Trump's Twitter missives, saying he doesn't expect a change in U.S.-Ukrainian relations in the future, "but if there is, we'll learn about it on Twitter."

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Angela Charlton, Lynn Berry and Inna Varenytsia in Kyiv contributed to this report

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Angela Charlton, Lynn Berry and Inna Varenytsia in Kyiv contributed to this report.