​Hunter Biden’s decision to join the board of gas company owned by a Ukrainian oligarch led to a falling out with his investment firm partner – the stepson of former Secretary of State John Kerry, according to a report on Sunday.

Chris Heinz ended his business relationship when Biden in 2014 took a position on the board of Burisma Holdings, which was owned by Mykola Zlochevsky, even as his father then-Vice President Joe Biden was serving in the Obama administration and cracking down on corruption in Ukraine, the Washington Post reported.

Hunter Biden, a partner with Heinz in the investment firm Rosemont Seneca, joined Burisma shortly after another of the firm’s partners, Devon Archer, also had accepted an invitation to the board.

Heinz parted ways with both men after raising concerns about corruption in Ukraine and questions about appearance.

“The lack of judgment in this matter was a major catalyst for Mr. Heinz ending his business relationships with Mr. Archer and Mr. Biden,” Heinz spokesman Chris Bastardi told the newspaper.

According to the report, Biden said he joined Burisma at the urging of the former Polish President Aleksander Kwasniewski, who was on the company’s board, and because he believed helping to create Ukraine’s energy independence would help ​shield the country from Russian leader Vladimir Putin.

The Burisma post has become part of the focus of a whistleblower’s complaint that claims President Trump contacted Ukrainian President Volodymyr to investigate Hunter Biden and his father, a 2020 Democratic presidential candidate.

​The allegations in the complaint led House Speaker Nancy Pelosi to launch an impeachment inquiry in the Democrat-majority House into the president.​

Trump and his allies have alleged that the former veep threatened to cancel $1 billion in loan guarantees to Ukraine unless it sacked top prosecutor Viktor Shokin, who at the time was investigating Burisma.

Ukraine’s Parliament voted Shokin out of office in March 2016.

The US, a number of Western countries, the European Union and the International Monetary Fund had claimed that Shokin was not aggressively prosecuting high-profile corruption cases.

Ukrainian officials have said there was no evidence the Bidens engaged in any wrongdoing.

“Joe Biden proudly fought for reform in Ukraine and his achievement of a goal the U.S., EU, IMF, and entire Ukrainian anti-corruption community all strongly supported was a profound victory for good government there,” Andrew Bates, a spokesman for the Biden campaign, said in a statement to the Washington Post.

Hunter Biden served on the Burisma board from 2014 to 2018.