US President Joe Biden's son Hunter Biden has offered to testify publicly next month to a House Republican impeachment inquiry of his father's Democratic administration while a leading lawmaker stuck to his demand of testimony behind closed doors.
Escalating a months-long investigation across three congressional committees, the Republican-controlled House of Representatives launched an impeachment inquiry into the president in September, which focuses on Hunter Biden's business dealings.
House Republicans allege Joe Biden and his family improperly traded access to Biden's office as vice president in US president Barack Obama's administration.
The White House denies wrongdoing.
As part of the inquiry, the House Oversight Committee has subpoenaed Hunter Biden, 53, to appear before the panel in a closed-door interview on December 13.
The panel also subpoenaed the president's brother, his late son's widow and Hunter Biden's business associates, among others.
The House Oversight Committee has held one public hearing as part of the probe, instead conducting most of their interviews in private.
Hunter Biden's lawyer on Tuesday criticised the panel's probe as "a fishing expedition" and an "empty investigation," telling the panel chairman a public hearing was the only way to prevent "your cloaked, one-sided process".
"We have seen you use closed-door sessions to manipulate, even distort the facts and misinform the public. We therefore propose opening the door," lawyer Abbe Lowell wrote committee chairman James Comer.
Hunter Biden would appear for a public hearing on December 13 or any other date in December that they could arrange, his lawyer said.
Comer said in a statement that the subpoena required Hunter Biden to appear for a deposition on December 13 but added that he should also have a chance to testify publicly at another time.
"Hunter Biden is trying to play by his own rules instead of following the rules required of everyone else. That won't stand with House Republicans," Comer said.
The White House has called the investigation a "smear campaign" that "has turned up zero evidence".
Donald Trump, the frontrunner for the 2024 Republican presidential nomination, has cheered on the impeachment probe.
During his four years in the Oval Office, he became the first president in US history to be impeached twice.
He was acquitted both times by the Senate.
Hunter Biden in October pleaded not guilty to charges that he lied about his drug use while buying a handgun, in the first-ever criminal prosecution of a sitting US president's child.
Special Counsel David Weiss brought those charges against Hunter Biden after an earlier proposed plea deal unravelled under questioning from a judge.
Weiss is still investigating whether the younger Biden can be charged for tax law violations.
The younger Biden earlier this month sought a federal court's permission to subpoena documents from Trump and top Justice Department officials in his administration as part of his defence against federal gun charges.
Australian Associated Press