US Secretary of State Mike Pompeo said Tuesday he felt duty bound to investigate whether Ukraine interfered in the 2016 election, without saying if he believed the widely debunked conspiracy theory.

President Donald Trump has sought a probe into whether Ukraine rather than Russia interfered in his election -- an idea already rejected by US intelligence and which a former White House official said was Russian propaganda.

"Any time there is information that indicates that any country has messed with American elections, we not only have a right but a duty to make sure we chase that down," Pompeo told reporters when asked about the Ukrainian theory.

Without mentioning Ukraine, the former CIA director said that he knew that "many countries" and non-state actors were trying to "undermine American democracy."

Pompeo said the United States should look into "whatever nation it is that we have information that so much as suggests there might have been interference or an effort to interfere in our elections."

"We have an obligation to make sure the American people get to go to the ballot box, cast ballots, in a way unimpacted by these malevolent actors trying to undermine our Western democratic values," he said.

US Secretary of State Mike Pompeo indicated an openness during a news conference to investigating Ukraine
US Secretary of State Mike Pompeo indicated an openness during a news conference to investigating Ukraine AFP / SAUL LOEB

US intelligence found that Russia interfered in the 2016 election to boost Trump over rival Hillary Clinton, although a subsequent probe by Robert Mueller found that the Trump campaign did not collude with Moscow.

In a July call to Ukrainian President Volodymyr Zelensky that triggered the ongoing impeachment inquiry, Trump asked for probes both into political rival Joe Biden and a theory that a Ukrainian company harbored a hacked server of the Democatic National Committee.

Appearing before the House Intelligence Committee last month, former National Security Council official Fiona Hill said that the Ukraine conspiracy narrative, pushed by Trump's lawyer Rudy Giuliani, was fictitious.

She warned against promoting "politically driven falsehoods that so clearly advance Russia's interests."

Zelensky, speaking to reporters Tuesday on a visit to Estonia, also dismissed suggestions that Ukraine interfered in the US election.

Ukraine has been seeking military aid to help fight Russian-backed separatists. The White House delayed the assistance, a key point in the impeachment inquiry.