WASHINGTON (Reuters) - White House advisers said they were concerned about a blackmail by a close associate of US President Donald Trump on Kiev, who issued warnings two weeks before President Trump asked his Ukrainian counterpart Volodymyr Zelinsky to investigate an opponent.

A transcript of the hearings released on Friday showed that Alexander Fendman and Fiona Hill, two influential members of the National Security Council, revealed at a closed-door congressional hearing that they had notified the White House legal department of their concerns since July 10.

They had attended a meeting in which US Ambassador to the European Union Gordon Sundland announced to a Ukrainian delegation that President Volodymyr Zelinsky would be received at the White House if he announced investigations of Democrat Joe Biden, who is well positioned to compete with Donald Trump in the 2020 presidential election. .

"Ambassador Sundland made it clear in the presence of the Ukrainians that he agreed with President Mike Malvini's office manager to hold a meeting if the investigations were going forward," said Fiona Hill, former assistant national security adviser John Bolton. Bolton, who was sacked in September, "was shocked ... and the meeting ended abruptly," he said.

Sundeland, a businessman who made a big donation to Trump's inauguration, continued his conversation with the Ukrainians in another White House room. Vindman said the ambassador clearly mentioned Joe Biden, whose son had long owned business in Ukraine.

Bolton, who was very angry, asked Hill to inform the National Security Council lawyer. He told him to help him, “Tell him I don't accept the behavior of the drug traffickers that Sundland and Malviny prepare.”

On another occasion, John Bolton officially banned his staff from speaking to Rudy Giuliani, Donald Trump's personal lawyer, who was contributing to the pressure on Ukraine. Hill said Bolton "said Rudy was a grenade that would blow everything up."

Despite these warnings, Trump asked Zielinski to "consider the situation" of Biden and talk to Giuliani.

Lieutenant-Colonel Findman, who was listening to the phone call immediately after the call ended, rushed to NSC lawyers to "share his concerns." Fiona Hill, who did not attend, was "shocked" when she read the text. "I read a lot of transcripts in two and a half years at the White House, but I haven't seen anything like that," she told members of Congress.

These testimonies weaken Trump's defense, which he claims is a victim of a "grim campaign" and called on his advisers to refrain from participating in the congressional investigation.