Hunter Biden said Tuesday he would testify before Congress next month, as part of a Republican-led impeachment investigation into President Joe Biden and his family.

"Your empty investigation has gone on too long wasting too many better-used resources. It should come to an end," Hunter Biden's attorney Abbe Lowell wrote in a letter to the chairman of the House Oversight Committee.

"Consequently, Mr. Biden will appear at such a public hearing on the date you noticed, December 13, or any date in December that we can arrange," wrote Lowell.

The defiant letter came weeks after House Oversight Chairman James Comer, R-Ky., subpoenaed the president's son and brother, and called for them to sit for closed-door depositions, as he conducts an impeachment inquiry into the president.

A spokesman for Comer did not immediately respond to CNBC's request for comment on the letter.

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