A State Department expert on Ukraine told lawmakers this week that he raised concerns about Hunter Biden’s job with a Ukrainian natural gas firm in 2015 — but Joe Biden’s staff blew him off because the then-veep was preoccupied with his other son Beau’s cancer battle, Fox News reported Friday.

Deputy Assistant Secretary of State George Kent, who testified behind closed doors before committees leading the House impeachment effort, said that he had qualms about Hunter Biden’s role on the board of the Ukrainian energy company Burisma.

The Washington Post first reported details of Kent’s testimony on Friday, which included his concern that Hunter Biden’s role in the company could complicate US diplomatic efforts with Ukrainian officials, and that he also raised conflict of interest concerns since the elder Biden was spearheading the Obama administration’s efforts to fight corruption in the country.

Kent also said that he feared that Hunter Biden’s position would make Ukrainian officials believe he was a backchannel to his father, Fox reported.

The Post first reported that the staff said they didn’t have the “bandwidth” to deal with the issue.

Biden’s campaign responded on Friday by ripping President Trump, who has repeatedly accused the Bidens of corruption.

“Donald Trump’s unprecedently corrupt administration is melting down because of the scandal he touched off by trying to get Ukraine to lie about Joe Biden – -and as the vice president said yesterday, he should release his tax returns or shut up,” a Biden campaign spokesperson told Fox.

“On Joe Biden’s watch, the US made eradicating corruption a centerpiece of our policies toward Ukraine including achieving the removal of an inept prosecutor who shielded wrongdoers from accountability.”

Kent had repeatedly raised concerns with the Obama administration about Burisma, such as in 2016 when he raised concerns with the administration about dropping a planned event with Burisma.

Sources also told Fox News that Kent told congressional investigators about the Obama administration’s efforts to remove Ukrainian prosecutor Viktor Shokin from his post.

At the time, Shokin was investigating Mykola Zlochevsky, the former minister of ecology and natural resources of Ukraine and Burisma’s founder.

Shokin was fired in April 2016, and his case was closed by the prosecutor who replaced him, Yuriy Lutsenko.

Biden once boasted that when he was vice president and leading the administration’s Ukraine policy he pressured Ukraine to fire Shokin — who was investigating Burisma Holdings while Hunter sat on the board.

The Bidens and their allies insist that Shokin’s firing had nothing to do with his son but was about his concern that Shokin himself was corrupt.

The EU and IMF also wanted Shokin gone.

Kent testified that while Shokin faced accusations of corruption, so did Lutsenko.

But sources said that Kent testified that while the US pushed hard for Shokin to be fired, no one ever pushed for Lutsenko to be fired, according to the Fox report.

Hunter Biden said this week he showed poor judgment by taking the Burisma gig, which paid him up to $50,000 a month, and admitted he would not have gotten the job if his name weren’t Biden.