Ukrainian President Vladimir Zelenskiy  has parted ways with Andriy Bohdan, who many said was evidence of an oligarch's influence over him.

Ukrainian President Volodymyr Zelenskiy has dismissed the chief of his administration, Andriy Bohdan, and replaced him with Andriy Yermak, an aide whose name has been linked to U.S. President Donald Trump's personal lawyer, Rudolph Giuliani.

The presidential decrees on relieving Bohdan from his duties and appointing Yermak were signed on February 11 and placed on the presidential website.

Evidence and testimony gathered during Trump's recent impeachment hearing shows Giuliani met with Yermak to "strongly" urge an investigation Trump wanted of Democratic rival Joe Biden and his son's ties to Ukrainian energy firm Burisma.

The Democratic-led House of Representatives impeached Trump in December for his alleged corruption involving the demands for the investigation, only the third such hearing against a president in the country's history.

The Senate later acquitted him on the impeachment charges.

Bohdan's appointment to the post in May last year, after Zelenskiy won the presidential election, sparked controversy as Bohdan used to be a lawyer for powerful tycoon Ihor Kolomoyskiy, who returned to Kyiv days ahead of Zelenskiy's inauguration after two years of self-imposed exile in Geneva and Tel Aviv.

Kolomoyskiy had left Ukraine to avoid criminal charges.

Under the previous president, Petro Poroshenko, the government had nationalized PrivatBank, which Kolomoyskiy once co-owned, and accused him of stealing $5.5 billion at a time when the war-torn country was being propped up by the International Monetary Fund (IMF), the United States, and the European Union.

Many said at the time that Kolomoyskiy returned to influence Zelenskiy's policies via Bohdan.

Kolomoyskiy's 1+1 television channel also aired Zelenskiy's comedy shows when he was an actor and supported his presidential bid with glowing wall-to-wall coverage during the campaign.