The White House has acknowledged it held up military aid to Ukraine as President Donald Trump pushed the country’s leader to investigate the Democratic National Committee in the 2016 US presidential campaign.

US acting chief of staff Mick Mulvaney said that Mr Trump did nothing wrong in linking the aid to Ukraine’s investigation. He said the probe would simply be part of the US Justice Department’s ongoing review of the 2016 election.

House Democrats, who are investigating whether the president engaged in a political quid pro quo when he asked the new Ukraine president to do a “favour”, immediately called it an admission of guilt.

Representative Adam Schiff, the chairman of the Intelligence Committee leading the impeachment probe, told reporters: “I think Mr Mulvaney’s acknowledgment means that things have gone from very, very bad to much, much worse.”

It is illegal to solicit or receive anything of value from a foreign entity in US elections.

The administration insists it held up military assistance to Ukraine in part because they wanted Ukraine’s co-operation in investigating whether the Democratic National Committee’s email servers were in Ukraine.

Donald Trump
Donald Trump put pressure on Ukraine’s leader (AP/Alex Brandon)

They were also looking at levels of assistance European nations were providing to Ukraine, he said.

Mr Mulvaney denies there was a quid pro quo and says “we do that all the time with foreign policy”.

He pointed to the example of the administration holding up aid to Central American countries to force them to change their policies on immigration.

Mr Trump ultimately released nearly 400 million US dollars (£310 million) in military and other aid to Ukraine.