US President Donald Trump on Saturday defended his personal attorney, Rudy Giuliani, who is reportedly under federal investigation over his dealings with Ukraine on the president’s behalf.

Taking to Twitter, Trump said, “So now they are after the legendary ‘crime buster’ and greatest Mayor in the history of NYC, Rudy Giuliani”.

“He may seem a little rough around the edges sometimes, but he is also a great guy and wonderful lawyer. Such a one-sided Witch Hunt going on in the USA. Deep State. Shameful!” Trump wrote.

Giuliani has emerged as the point man in Trump’s alleged drive to pressure Ukraine to dig up dirt on Democratic presidential hopeful Joe Biden and help Trump win re-election.

Earlier this month, Ukraine’s former president had said that he discussed investments with President Donald Trump’s attorney, Rudy Giuliani, in 2017, but that he never discussed Ukrainian companies with any US official.

Like many Ukrainians, former President Petro Poroshenko is trying to distance himself from the US impeachment enquiry into Trump, triggered by a phone call between the American leader and Poroshenko’s successor, Volodymyr Zelenskiy.

Giuliani wanted Ukraine to investigate Biden, whose son Hunter served on the board of the Ukrainian gas company Burisma.

Giuliani, a former federal prosecutor and ex-mayor of New York City, has acknowledged that he and two associates worked with Ukrainian prosecutors to collect information on Biden, his son Hunter and the US ambassador to Ukraine Marie Yovanovitch, who was recalled in May.

Under US lobbying law, Americans who contact the US government while acting at the direction or request of foreign politicians or a foreign government must report this to the Justice Department, regardless of whether they are paid by the foreign party.

The two Giuliani associates were arrested this week as they tried to flee the country and charged with campaign finance violations in connection with the Ukraine affair.