Joe Biden and his son Hunter Biden attend an NCAA basketball game between Georgetown University and Duke University in Washington, January 30, 2010.

A woman who had a love child by Hunter Biden, son of Democratic presidential front-runner Joe Biden, is demanding that he formally divulge how much he earned from working for a Ukraine gas company that plays a key role in the ongoing impeachment proceedings against President Donald Trump.

Arkansas resident Lunden Alexis Roberts also is demanding in her pending paternity case that Hunter Biden admit that he could have continued serving as a board member of the company, Burisma.

And she is asking him to admit that his decision not to continue on the board was a "voluntary" one, according to her court filing in Independence County Circuit Court in Arkansas.

Hunter Biden, a 49-year-old lawyer, reportedly earned around $50,000 per month while serving on Burisma's board from April 2014 until this April.

Roberts, 28, in court papers filed Monday demanded that Hunter admit that he or any entity he owned or controlled "received money from a Chinese person, entity or corporation for foreign (meaning international) and domestic (meaning United States) investment purposes."

Roberts is seeking the admissions in connection with her application for child support payments from Hunter.

Hunter Biden's lawyers declined to comment Tuesday to CNBC about the new filing.

Trump is on the verge of being impeached by the House of Representatives because of his pressuring of Ukraine's president to announce he was investigating Joe Biden, who is a former vice president, and Hunter Biden in connection with Hunter's work for Burisma.

Trump withheld almost $400 million in congressionally appropriated military aid while he was pushing Ukraine to launch that probe, as well as another one into a conspiracy theory that Ukraine interfered in the 2016 U.S. presidential election.

Trump has suggested that Hunter Biden, who had no expertise in the natural gas field, won a spot on Burisma's board because his father at the time was vice president under President Barack Obama and was responsible for U.S. policy regarding Ukraine.

Trump also has suggested there was corruption involved in Hunter's investments in China.