U.S. President Donald Trump on Friday accused a witness in the Democratic-led impeachment inquiry of lying and offered an explanation for his controversial use of his personal lawyer Rudy Giuliani on Ukraine policy, saying Giuliani's crime-fighting abilities were needed to deal with a corrupt country. 

Trump made his remarks the day after the fifth and final scheduled day of public hearings in the U.S. House of Representatives inquiry, which threatens his presidency even as he seeks re-election in November 2020.

The Republican president took issue with testimony on Thursday by David Holmes, a U.S. embassy official in Ukraine. Holmes said under oath that at a Kiev restaurant he overheard a July 26 cellphone conversation in which Trump loudly pressed Gordon Sondland, the U.S. ambassador to the European Union, for details on whether Ukraine would carry out politically motivated investigations the president was seeking. 

"I guarantee you that never took place," Trump told media, "That was a total phony deal."

Trump appointed Sondland to the envoy post after the wealthy Oregon hotelier donated one million U.S. dollars to his inaugural committee. While Sondland in testimony described an easygoing relationship between the two, Trump said on Friday he had spoken with him "a few times," adding, "I hardly know him, OK?"

Bolton: White House blocked my Twitter account 

In another development, Trump's former national security adviser John Bolton accused the White House of blocking his access to his personal Twitter account after he left his job in the Trump administration in September. 

"We have now liberated the Twitter account, previously suppressed unfairly in the aftermath of my resignation as National Security Advisor," Bolton told his more than 790,000 followers in his first tweets since resigning in September. 

"In full disclosure, the @WhiteHouse never returned access to my Twitter account. Thank you to @twitter for standing by their community standards and rightfully returning control of my account," he wrote. 

Bolton did not explain how the White House had accomplished this but in his first Twitter post since his departure asked if it had been done "out of fear of what I may say?"

Trump denied in a TV interview that Bolton's access had been blocked by the White House. 

Bolton's return to the platform came at a sensitive time for the administration. He is among various U.S. officials described as being alarmed at Trump's controversial use of his personal lawyer Rudy Giuliani on Ukraine policy, which is under intense scrutiny in a Democratic-led impeachment inquiry.

Trump call 

A focus of the inquiry is a July 25 telephone call in which Trump asked Ukrainian President Volodymyr Zelenskiy to open two investigations. 

One involved Joe Biden, a top contender for the Democratic nomination to face Trump in the 2020 presidential election, and his son Hunter Biden, who had worked for Ukrainian energy company Burisma. Trump has accused Biden of corruption, but has not provided evidence. Biden has denied wrongdoing. 

The other investigation involved a debunked conspiracy theory promoted by Trump and his allies that Ukraine meddled in the 2016 U.S. presidential election to hurt his candidacy and boost Democratic rival Hillary Clinton. Trump touted that theory again on Friday.

U.S. intelligence agencies and former Special Counsel Robert Mueller determined that Russia used a campaign of propaganda and hacking to interfere in the election to try to help Trump win. 

Giuliani 'a great person'

Testimony in the impeachment inquiry has shown that Trump in May instructed top U.S. officials to work with Giuliani on Ukraine policy. This came after the president removed Marie Yovanovitch as U.S. ambassador to Ukraine at Giuliani's urging even as the former mayor was pressing officials in Kiev to conduct the two investigations. 

During the hearings, current and former White House officials and diplomats voiced alarm at Giuliani's activities. 

Trump, however, insisted Giuliani was the right person for the job.

"He's like an iconic figure in this country for two reasons. He was the greatest mayor in the history of New York and he was the greatest crime fighter probably in the last 50 years," Trump said of Giuliani, who previously served as the mayor of the largest U.S. city and as a federal prosecutor. 

"He's also a friend of mine. He's a great person," Trump added. "When you're dealing with a corrupt country - if Rudy Giuliani - he's got credentials because of his reputation... When Rudy Giuliani goes there and you hear it's a corrupt country, I mean, it means a lot.” 

Trump did not address what he actually told Giuliani to do.

Corruption fighter?

Democrats are also looking into whether Trump abused his power by withholding 391 million U.S. dollars in security aid to Ukraine as leverage to pressure Kiev into digging up dirt on his political adversaries. 

The money - approved by the U.S. Congress to help Ukraine combat Russia-backed separatists in the eastern part of the country - was provided to Ukraine in September only after the controversy spilled into public view. 

Trump's allies have argued that the two investigations were not aimed at gaining a domestic political advantage but rather at combating corruption in a country receiving millions of dollars in U.S. aid. 

The president said Ukraine is "known as being the third most corrupt country in the world."

If the Democratic-led House approved articles of impeachment - formal charges - against Trump, the Senate would then hold a trial on whether to convict Trump and remove him from office. Trump's fellow Republicans control the Senate and have shown little support for removing him. "I want a trial," said Trump. 

(Cover: U.S. President Donald Trump speaks about the impeachment inquiry during a tour of the Flextronics computer manufacturing facility where Apple's Mac Pros are assembled in Austin, Texas, November 20, 2019. /VCG Photo)

(With input from Reuters)