US President Donald Trump abused his power of office, a key Congressional committee from the Democratic-controlled House of Representatives has alleged in a report based on its impeachment hearings against the President.

'The evidence is clear that President Trump used the power of his office to pressure Ukraine into announcing investigations into his political rival, former vice-president Joe Biden, and a debunked conspiracy theory that it was Ukraine, not Russia, that interfered in the 2016 election,' said chairs of the three House Committees after the release of a report on Tuesday.

Released by the House Permanent Select Committee on Intelligence, the 'Trump-Ukraine Impeachment Inquiry Report' was written by the staff of the House Intelligence, Oversight and Reform and Foreign Affairs Committees.

In a joint statement, intelligence committee chairman Adam Schiff, oversight committee chairwoman Carolyn B. Maloney and foreign affairs committee chairman Eliot Engel alleged that the evidence is clear that Trump conditioned official acts on the public announcement of these investigations: a coveted White House visit and critical US military assistance Ukraine needed to fight its Russian adversary.

The White House dismissed the report and slammed the House Democrats.

'At the end of a one-sided sham process, chairman Schiff and the Democrats utterly failed to produce any evidence of wrongdoing by President Trump,' White House press secretary Stephanie Grisham said.

'This report reflects nothing more than their frustrations. Chairman Schiff's report reads like the ramblings of a basement blogger straining to prove something when there is evidence of nothing,' Grisham said.

The three lawmakers alleged that evidence is clear that after his scheme to secure foreign help in his reelection was uncovered, Trump engaged in categorical and unprecedented obstruction in order to cover-up his misconduct.

'These matters are not seriously contested. To the contrary, they make it plain that President Trump abused the power of his office for personal and political gain, at the expense of our national security,' they alleged.

'The President's actions have damaged our national security, undermined the integrity of the next election, and violated his oath of office. They have also challenged the very core of our Constitutional system of checks and balances, separation of powers, and rule of law,' the joint statement said.

Now it will be up to the Congress to determine whether these acts rise to the level of an impeachable offense, whether the President shall be held to account, and whether United States is committed to the rule of law or, instead, whether a President who uses the power of his office to coerce foreign interference in a US election is something that Americans must simply 'get over', they said.

According to the executive summary of the report impeachment inquiry into Trump, 'uncovered a months-long effort' by him 'to use the powers of his office to solicit foreign interference' on his behalf in the 2020 election.

Trump's scheme subverted US foreign policy towards Ukraine and undermined US national security in favour of two politically-motivated investigations that would help his presidential re-election campaign, the report alleges.

'The President demanded that the newly-elected Ukrainian President, Volodymyr Zelensky, publicly announce investigations into a political rival that he apparently feared the most, former vice-president Joe Biden, and into a discredited theory that it was Ukraine, not Russia, that interfered in the 2016 presidential election,' it said.

'To compel the Ukrainian President to do his political bidding, President Trump conditioned two official acts on the public announcement of the investigations: a coveted White House visit and critical US military assistance Ukraine needed to fight its Russian adversary, the report said.

Trump has described the impeachment proceedings as a hoax.

The report alleges that Trump ordered the suspension of USD 391 million in vital military assistance urgently needed by Ukraine, a strategic partner, to resist Russian aggression.

'Because the aid was appropriated by Congress, on a bipartisan basis, and signed into law by the President, its expenditure was required by law. Acting directly and through his subordinates within the US government, the President withheld from Ukraine this military assistance without any legitimate foreign policy, national security, or anti-corruption justification, it said.

'The President did so despite the longstanding bipartisan support of Congress, uniform support across federal departments and agencies for the provision to Ukraine of the military assistance, and his obligations under the Impoundment Control Act,' it alleged.