Donald Trump has denounced the whistleblower report (File)

A whistleblower report released by a congressional panel on Thursday said President Donald Trump used his office to solicit Ukraine's interference in the 2020 election to advance his personal political interests, risking US national security.

The Democratic-led US House of Representatives Intelligence Committee released a declassifed version of the report made by the whistleblower, which triggered weeks of controversy and prompted House Speaker Nancy Pelosi to launch a formal impeachment inquiry into the Republican president.

"I am deeply concerned that the actions described below constitute 'a serious or flagrant problem, abuse, or violation of law or executive order' that 'does not include differences of opinion concerning public policy matters,' consistent with the definition of an 'urgent concern'," the report said.

Trump pressed Ukrainian President Volodymyr Zelenskiy to investigate Democratic presidential front-runner Joe Biden, in coordination with US Attorney General William Barr and Trump's personal lawyer Rudy Giuliani, according to a summary of a July telephone call released by the Trump administration on Wednesday.

Moments after the whistleblower report was made public, the committee began a hearing at which acting Director of National Intelligence, Joseph Maguire, was set to testify about the document after refusing for weeks to share the report with Congress. Saying that more than six White House officials had made contact about Trump's communication with Ukraine, the report cited concerns that efforts to put pressure on Ukraine "pose risks to US national security," undermining efforts "to deter and counter foreign interference in US elections."

Trump has denied wrongdoing and accused Democrats of trying to destroy him politically. A federal law required that the report be sent to lawmakers after an inspector general determined that it was urgent and credible. Shortly before the hearing, the intelligence committee's chairman, Democratic Representative Adam Schiff, announced that it had received the declassified complaint and released it to the public.

"This complaint should never have been withheld from Congress. It exposed serious wrongdoing, and was found both urgent and credible by the Inspector General," Ms Schiff said in a statement

The whistleblower complaint concerns a July 25 telephone call in which Mr Trump pressed Volodymyr Zelenskiy to investigate Mr Biden and his son Hunter, who had worked for a company drilling for gas in Ukraine.

The whistleblower report said Mr Giuliani was a central figure in the alleged interference effort, and that Mr Barr also seemed to be involved.

And it said that multiple US officials said Ukrainian leaders were led to believe that Mr Trump would only talk to Mr Zelenskiy if the Ukrainian leader would "play ball."

Mr Trump quickly denounced the report. "The democrats are trying to destroy the republican party and all that it stands for," Mr Trump exclaimed on Twitter.

"Stick together, play their game, and fight hard republicans. Our country is at stake," he added.

Under the US Constitution, the House has the power to impeach a president for "high crimes and misdemeanors." No president has ever been removed from office through impeachment.

Democrats control the House and Trump's fellow Republicans control the Senate.The United States has been giving military aid to Ukraine since Russia's annexation of Crimea in 2014

The $391.5 million in aid at issue in the current controversy was approved by Congress to help Ukraine deal with an insurgency by Russian-backed separatists in the eastern part of the country.

The details of the July 25 call drew furious reactions from Democrats, who accused Trump of soliciting Ukraine's help to smear Biden, who has led in polls among Democratic candidates seeking to challenge the Republican president in the November 2020 election.