US Ambassador to the EU Gordon Sondland said he worked with Rudy Giuliani, Trump's lawyer, on Ukraine issues "on orders from the President".

Sondland told the House Intelligence Committee on a November 20 hearing that Giuliani urged Ukrainian President Volodymyr Zelenskiy to investigate former US Vice President Joe Biden and Hunter's son "a reciprocal agreement to orchestrate arrange a White House visit "for Ukrainian leaders.

Sondland also said US Secretary of State Mike Pompeo knew this and "fully supported" their efforts to put pressure on Ukraine.

Hunter was on the board of Burisma energy company, one of Ukraine's largest gas businesses, when his father was vice president under Barack Obama. President Trump and his confidant suspects that Biden used his power to keep Burisma from investigating allegations of corruption in 2016. Biden was Trump's top rival in the race to the White House in 2020.

According to Sondland, President Trump ordered him and two other senior officials to work with Giuliani, who refused to cooperate with the impeachment investigation.

"We don't want to work with Giuliani," Sondland said. "We understand that if we refuse to work with Giuliani, we will lose an important opportunity to strengthen relations between the United States and Ukraine. Therefore, we follow orders from the President."

The US House of Representatives opened a Trump impeachment investigation in September after an anonymous whistleblower accused the US president of urging his Ukrainian counterpart to investigate Biden's father and son in a phone call on July 25.

About a week before the phone call, Trump postponed a nearly $ 400 million military aid to Ukraine, sparking speculation about the White House boss's motives. However, Trump explained he postponed aid because he wanted other European countries to also support Kiev.