WASHINGTON - A top aide to Vice-President Mike Pence said Wednesday that a conversation described by U.S. European Union Ambassador Gordon Sondland about a link between military aid for Ukraine and investigations “never happened.”

Sondland testified Wednesday that he spoke with Pence before a Sept. 1 meeting with Ukrainian officials “that I had concerns that the delay in aid had become tied to the issue of investigations.”

In a carefully worded statement, Marc Short, Pence’s chief of staff, denied that Pence spoke to Sondland “about investigating the Bidens, Burisma, or the conditional release of financial aid to Ukraine based upon potential investigations,” referencing the gas company where Joe Biden’s son Hunter served on the board.

Short added that Sondland was “never alone” with Pence during the Sept. 1 trip to Poland.

“This alleged discussion recalled by Ambassador Sondland never happened,” Short said.

Democrats pressed Sondland on the denial after the Pence statement was released, with Sondland saying he never indicated there was a one-on-one meeting with Pence. Earlier Sondland testified that Pence didn’t express surprise when he informed the vice-president about his concerns that are now at the centre of the impeachment probe. He said he did not “recall any substantive response” from Pence.

The House impeachment inquiry focuses significantly on allegations that President Donald Trump sought investigations of Biden and his son — and the discredited idea that Ukraine rather than Russia interfered in the 2016 U.S. election — in return for the badly needed military aid as well as a White House visit. Trump has denied doing anything wrong.

Pence aides have previously maintained that the vice-president was unaware of efforts to push Ukrainian President Volodymyr Zelenskiy to release a statement announcing investigations. And Pence has said no such push came up during his September meeting with Zelenskiy in Warsaw, even as the leaders discussed the U.S. military aid that was under review.

Pence press secretary Katie Waldman said Pence was also unaware of the “brief pull-aside conversation” that Sondland reported having with a top aide to Zelenskiy following the Pence-Zelenskiy meeting. Sondland has said he told Andriy Yermak that the “resumption of U.S. aid would likely not occur until Ukraine provided the public anti-corruption statement that we had been discussing for many weeks.”