US national security officials complained about President Donald Trump's dealings with Ukraine both before his phone call with President Volodymyr Zelensky and immediately after it, The Washington Post newspaper has reported.
The security officials -- at least four of them -- raised their concerns with National Security Council legal advisor John Eisenberg, the Post claims.
The US House of Representatives is conducting an impeachment inquiry into Trump over alleged abuse of power during the 25 July call in which he asked Ukrainian leader Zelensky to conduct a probe of potential 2020 White House rival Joe Biden and his son, who served on the board of a Ukrainian gas company.
Even before the call, security officials were concerned about the removal of the US ambassador to Ukraine in May, and also about efforts by Trump's personal lawyer Rudy Giuliani to spread conspiracies involving Ukraine and indications that Trump wanted Zelensky to offer up potentially damaging information about Biden, according to the newspaper.
The security officials became even more unnerved after the call, in which Trump asked Zelensky to "look into" Biden family activities in Ukraine.
Senior officials, including then-national security advisor John Bolton, received complaints about the call within minutes, the report says.
Trump has denied he did anything wrong, calling his conversation with Zelensky "perfect".
The White House said in a statement on Tuesday that it would not cooperate in the impeachment inquiry, calling the proceedings "constitutionally invalid".