WASHINGTON (REUTERS) - A former White House aide who helped coordinate the Trump administration's response to the coronavirus pandemic sharply criticised US President Donald Trump in a video released on Thursday (Sept 17) and said she planned to vote for Democrat Joe Biden.

Ms Olivia Troye, who was an aide to Vice-President Mike Pence, served as a top organiser for the White House Coronavirus Task Force that Mr Pence leads.

A lifelong Republican, Ms Troye, who has since left the White House, said in a video released by the group Republican Voters Against Trump that the administration knew around mid-February that Covid-19 would become a big pandemic in the United States.

"But the president didn't want to hear that because his biggest concern was that we were in an election year and how was this going to affect what he considered to be his record of success," she said.

Ms Troye said it was shocking to see Mr Trump, who downplayed the virus in its early stages, referring to it as a hoax and saying everything would be OK.

"The truth is he doesn't actually care about anyone else but himself," she said in the video. "If the president had taken this virus seriously .... he would have slowed the virus spread, he would have saved lives."

Mr Trump told reporters he did not know Ms Troye. He said she was let go but wrote a "beautiful letter" praising the administration on her way out.

"I never met her," he said.

In that letter, released by the White House, Ms Troye said it has been an "absolute honour" to work on the coronavirus task force but did not offer praise for Mr Trump or Mr Pence.

Mr Pence, in comments to reporters, described Ms Troye's words as sounding like those of a disgruntled employee who was playing politics during an election year.

White House spokesman Judd Deere said Ms Troye was not directly involved in the coronavirus task force and did not meet with Mr Trump privately. He called her statements "flat out inaccurate."

Mr Biden, a former vice-president, has sharply criticised Mr Trump's handling of the pandemic, which has caused more than 195,000 US deaths, and promised to institute a national plan to fight it if elected on Nov 3.

Ms Troye said it was an honour to serve in the White House but she wrestled during her time there with whether she made a difference because the president's actions were detrimental to the administration's efforts on the virus.

"It was awful," she said. "It was terrifying."